minimizing false positives: Topics by Science.gov

Sample records for minimizing false positives

Reducing false-positive incidental findings with ensemble genotyping and logistic regression based variant filtering methods.

PubMed

Hwang, Kyu-Baek; Lee, In-Hee; Park, Jin-Ho; Hambuch, Tina; Choe, Yongjoon; Kim, MinHyeok; Lee, Kyungjoon; Song, Taemin; Neu, Matthew B; Gupta, Neha; Kohane, Isaac S; Green, Robert C; Kong, Sek Won

2014-08-01

As whole genome sequencing (WGS) uncovers variants associated with rare and common diseases, an immediate challenge is to minimize false-positive findings due to sequencing and variant calling errors. False positives can be reduced by combining results from orthogonal sequencing methods, but costly. Here, we present variant filtering approaches using logistic regression (LR) and ensemble genotyping to minimize false positives without sacrificing sensitivity. We evaluated the methods using paired WGS datasets of an extended family prepared using two sequencing platforms and a validated set of variants in NA12878. Using LR or ensemble genotyping based filtering, false-negative rates were significantly reduced by 1.1- to 17.8-fold at the same levels of false discovery rates (5.4% for heterozygous and 4.5% for homozygous single nucleotide variants (SNVs); 30.0% for heterozygous and 18.7% for homozygous insertions; 25.2% for heterozygous and 16.6% for homozygous deletions) compared to the filtering based on genotype quality scores. Moreover, ensemble genotyping excluded > 98% (105,080 of 107,167) of false positives while retaining > 95% (897 of 937) of true positives in de novo mutation (DNM) discovery in NA12878, and performed better than a consensus method using two sequencing platforms. Our proposed methods were effective in prioritizing phenotype-associated variants, and an ensemble genotyping would be essential to minimize false-positive DNM candidates. © 2014 WILEY PERIODICALS, INC.
Reducing false positive incidental findings with ensemble genotyping and logistic regression-based variant filtering methods

PubMed Central

Hwang, Kyu-Baek; Lee, In-Hee; Park, Jin-Ho; Hambuch, Tina; Choi, Yongjoon; Kim, MinHyeok; Lee, Kyungjoon; Song, Taemin; Neu, Matthew B.; Gupta, Neha; Kohane, Isaac S.; Green, Robert C.; Kong, Sek Won

2014-01-01

As whole genome sequencing (WGS) uncovers variants associated with rare and common diseases, an immediate challenge is to minimize false positive findings due to sequencing and variant calling errors. False positives can be reduced by combining results from orthogonal sequencing methods, but costly. Here we present variant filtering approaches using logistic regression (LR) and ensemble genotyping to minimize false positives without sacrificing sensitivity. We evaluated the methods using paired WGS datasets of an extended family prepared using two sequencing platforms and a validated set of variants in NA12878. Using LR or ensemble genotyping based filtering, false negative rates were significantly reduced by 1.1- to 17.8-fold at the same levels of false discovery rates (5.4% for heterozygous and 4.5% for homozygous SNVs; 30.0% for heterozygous and 18.7% for homozygous insertions; 25.2% for heterozygous and 16.6% for homozygous deletions) compared to the filtering based on genotype quality scores. Moreover, ensemble genotyping excluded > 98% (105,080 of 107,167) of false positives while retaining > 95% (897 of 937) of true positives in de novo mutation (DNM) discovery, and performed better than a consensus method using two sequencing platforms. Our proposed methods were effective in prioritizing phenotype-associated variants, and ensemble genotyping would be essential to minimize false positive DNM candidates. PMID:24829188
An Evaluation of Unit and ½ Mass Correction Approaches as a Means of Minimizing the False Positives Produced by M+2 species in US EPA Method 200.8 using ICP-MS

EPA Science Inventory

Rare earth elements (REE) and certain alkaline earths can produce M+2 interferences in ICP-MS because they have sufficiently low second ionization energies. Four REEs (150Sm, 150Nd, 156Gd and 156Dy) produce false positives on 75As and 78Se and 132Ba can produce a false positive ...
Gas insufflation of minimal preparation CT of the colon reduces false-positives

PubMed Central

Slater, A; North, M; Hart, M; Ferrett, C

2012-01-01

Objectives Minimal preparation CT of the colon (MPCT colon) is used for investigation of suspected colorectal cancer in frail and/or elderly patients who would be expected to tolerate laxative bowel preparation poorly. Although it has good sensitivity for colorectal cancer it has a poor specificity. We wished to investigate whether distension of the colon with carbon dioxide alone would reduce the number of false-positives, but without making the test arduous or excessively uncomfortable. Methods 134 patients were recruited and underwent MPCT colon with gas insufflation and antispasmodics. Results were compared with a cohort of 134 patients undergoing standard protocol MPCT colon. The numbers of false-positives were compared, as was reader confidence. All trial patients were given a questionnaire documenting their experience. Results The number of false-positives was 15% in the control group and 5% in the trial group; this difference was statistically significant, (p=0.01). Reader confidence was increased in the trial group. Patient tolerance was good, with 95% saying they would have the test again. Conclusion Use of gas insufflation and antispasmodics reduces the false-positives from 15% to 5% without adversely affecting patient tolerance. PMID:21224295
An Evaluation of Unit and ½ Mass Correction Approaches as a Means of Minimizing the False Positives Produced by M+2 species in US EPA Method 200.8 using ICP-MS (webinar presentation)

EPA Science Inventory

Rare earth elements (REE) and certain alkaline earths can produce M+2 interferences in ICP-MS because they have sufficiently low second ionization energies. Four REEs (150Sm, 150Nd, 156Gd and 156Dy) produce false positives on 75As and 78Se and 132Ba can produce a false positive ...
[Roaming through methodology. XXXII. False test results].

PubMed

van der Weijden, T; van den Akker, M

2001-05-12

The number of requests for diagnostic tests is rising. This leads to a higher chance of false test results. The false-negative proportion of a test is the proportion of negative test results among the diseased subjects. The false-positive proportion is the proportion of positive test results among the healthy subjects. The calculation of the false-positive proportion is often incorrect. For example, instead of 1 minus the specificity it is calculated as 1 minus the positive predictive value. This can lead to incorrect decision-making with respect to the application of the test. Physicians must apply diagnostic tests in such a way that the risk of false test results is minimal. The patient should be aware that a perfectly conclusive diagnostic test is rare in medical practice, and should more often be informed of the implications of false-positive and false-negative test results.
Minimizing false positive error with multiple performance validity tests: response to Bilder, Sugar, and Hellemann (2014 this issue).

PubMed

Larrabee, Glenn J

2014-01-01

Bilder, Sugar, and Hellemann (2014 this issue) contend that empirical support is lacking for use of multiple performance validity tests (PVTs) in evaluation of the individual case, differing from the conclusions of Davis and Millis (2014), and Larrabee (2014), who found no substantial increase in false positive rates using a criterion of failure of ≥ 2 PVTs and/or Symptom Validity Tests (SVTs) out of multiple tests administered. Reconsideration of data presented in Larrabee (2014) supports a criterion of ≥ 2 out of up to 7 PVTs/SVTs, as keeping false positive rates close to and in most cases below 10% in cases with bona fide neurologic, psychiatric, and developmental disorders. Strategies to minimize risk of false positive error are discussed, including (1) adjusting individual PVT cutoffs or criterion for number of PVTs failed, for examinees who have clinical histories placing them at risk for false positive identification (e.g., severe TBI, schizophrenia), (2) using the history of the individual case to rule out conditions known to result in false positive errors, (3) using normal performance in domains mimicked by PVTs to show that sufficient native ability exists for valid performance on the PVT(s) that have been failed, and (4) recognizing that as the number of PVTs/SVTs failed increases, the likelihood of valid clinical presentation decreases, with a corresponding increase in the likelihood of invalid test performance and symptom report.
False negative rates in Drosophila cell-based RNAi screens: a case study

PubMed Central

2011-01-01

Background High-throughput screening using RNAi is a powerful gene discovery method but is often complicated by false positive and false negative results. Whereas false positive results associated with RNAi reagents has been a matter of extensive study, the issue of false negatives has received less attention. Results We performed a meta-analysis of several genome-wide, cell-based Drosophila RNAi screens, together with a more focused RNAi screen, and conclude that the rate of false negative results is at least 8%. Further, we demonstrate how knowledge of the cell transcriptome can be used to resolve ambiguous results and how the number of false negative results can be reduced by using multiple, independently-tested RNAi reagents per gene. Conclusions RNAi reagents that target the same gene do not always yield consistent results due to false positives and weak or ineffective reagents. False positive results can be partially minimized by filtering with transcriptome data. RNAi libraries with multiple reagents per gene also reduce false positive and false negative outcomes when inconsistent results are disambiguated carefully. PMID:21251254
Challenges associated with post-deployment screening for mild traumatic brain injury in military personnel.

PubMed

Iverson, Grant L; Langlois, Jean A; McCrea, Michael A; Kelly, James P

2009-11-01

There is ongoing debate regarding the epidemiology of mild traumatic brain injury (MTBI) in military personnel. Accurate and timely estimates of the incidence of brain injury and the prevalence of long-term problems associated with brain injuries among active duty service members and veterans are essential for (a) operational planning, and (b) to allocate sufficient resources for rehabilitation and ongoing services and supports. The purpose of this article is to discuss challenges associated with post-deployment screening for MTBI. Multiple screening methods have been used in military, Veterans Affairs, and independent studies, which complicate cross-study comparisons of the resulting epidemiological data. We believe that post-deployment screening is important and necessary--but no screening methodology will be flawless, and false positives and false negatives are inevitable. Additional research is necessary to refine the sequential screening methodology, with the goal of minimizing false negatives during initial post-deployment screening and minimizing false positives during follow-up evaluations.
False-positive psychology: undisclosed flexibility in data collection and analysis allows presenting anything as significant.

PubMed

Simmons, Joseph P; Nelson, Leif D; Simonsohn, Uri

2011-11-01

In this article, we accomplish two things. First, we show that despite empirical psychologists' nominal endorsement of a low rate of false-positive findings (≤ .05), flexibility in data collection, analysis, and reporting dramatically increases actual false-positive rates. In many cases, a researcher is more likely to falsely find evidence that an effect exists than to correctly find evidence that it does not. We present computer simulations and a pair of actual experiments that demonstrate how unacceptably easy it is to accumulate (and report) statistically significant evidence for a false hypothesis. Second, we suggest a simple, low-cost, and straightforwardly effective disclosure-based solution to this problem. The solution involves six concrete requirements for authors and four guidelines for reviewers, all of which impose a minimal burden on the publication process.
False positives in psychiatric diagnosis: implications for human freedom.

PubMed

Wakefield, Jerome C

2010-02-01

Current symptom-based DSM and ICD diagnostic criteria for mental disorders are prone to yielding false positives because they ignore the context of symptoms. This is often seen as a benign flaw because problems of living and emotional suffering, even if not true disorders, may benefit from support and treatment. However, diagnosis of a disorder in our society has many ramifications not only for treatment choice but for broader social reactions to the diagnosed individual. In particular, mental disorders impose a sick role on individuals and place a burden upon them to change; thus, disorders decrease the level of respect and acceptance generally accorded to those with even annoying normal variations in traits and features. Thus, minimizing false positives is important to a pluralistic society. The harmful dysfunction analysis of disorder is used to diagnose the sources of likely false positives, and propose potential remedies to the current weaknesses in the validity of diagnostic criteria.
Evaluation of Second-Level Inference in fMRI Analysis

PubMed Central

Roels, Sanne P.; Loeys, Tom; Moerkerke, Beatrijs

2016-01-01

We investigate the impact of decisions in the second-level (i.e., over subjects) inferential process in functional magnetic resonance imaging on (1) the balance between false positives and false negatives and on (2) the data-analytical stability, both proxies for the reproducibility of results. Second-level analysis based on a mass univariate approach typically consists of 3 phases. First, one proceeds via a general linear model for a test image that consists of pooled information from different subjects. We evaluate models that take into account first-level (within-subjects) variability and models that do not take into account this variability. Second, one proceeds via inference based on parametrical assumptions or via permutation-based inference. Third, we evaluate 3 commonly used procedures to address the multiple testing problem: familywise error rate correction, False Discovery Rate (FDR) correction, and a two-step procedure with minimal cluster size. Based on a simulation study and real data we find that the two-step procedure with minimal cluster size results in most stable results, followed by the familywise error rate correction. The FDR results in most variable results, for both permutation-based inference and parametrical inference. Modeling the subject-specific variability yields a better balance between false positives and false negatives when using parametric inference. PMID:26819578
False-positive alarms for bacterial screening of platelet concentrates with BacT/ALERT new-generation plastic bottles: a multicenter pilot study.

PubMed

Hundhausen, T; Müller, T H

2005-08-01

The microbial detection system BacT/ALERT (bioMérieux) is widely used to monitor bacterial contamination of platelet concentrates (PCs). Recently, the manufacturer introduced polycarbonate culture bottles and a modified pH-sensitive liquid emulsion sensor as microbial growth indicator. This reconfigured assay was investigated in a routine setting. In each of eight transfusion centers, samples from 500 consecutive PCs were monitored for 1 week. For all PCs with a positive BacT/ALERT signal, retained samples and, if available, original PC containers and concomitant red blood cell concentrates were analyzed independently. Initially BacT/ALERT-positive PCs without bacterial identification in any sample were defined as false-positive. BacT/ALERT-positive PCs with bacteria in the first sample only were called potentially positive. PCs with bacteria in the first sample and the same strain in at least one additional sample were accepted as positive. Five PCs (0.13%) were positive, 9 PCs (0.23%) were potentially positive, and 35 PCs (0.9%) were false-positive. The rate of false-positive BacT/ALERT results varied substantially between centers (<0.2%-3.2%). Tracings from false-positive cultures lacked an exponential increase of the signal during incubation. Most of these false-positives were due to malfunctioning cells in various BacT/ALERT incubation units. Careful assessment of individual tracings of samples with positive signals helps to identify malfunctioning incubation units. Their early shutdown or replacement minimizes the high rate of unrectifiable product rejects attributed to false-positive alarms and avoids unnecessary concern of doctors and patients after conversion to a reconfigured BacT/ALERT assay.
The role of ethics in shale gas policies.

PubMed

de Melo-Martín, Inmaculada; Hays, Jake; Finkel, Madelon L

2014-02-01

The United States has experienced a boom in natural gas production due to recent technological innovations that have enabled natural gas to be produced from unconventional sources, such as shale. There has been much discussion about the costs and benefits of developing shale gas among scientists, policy makers, and the general public. The debate has typically revolved around potential gains in economics, employment, energy independence, and national security as well as potential harms to the environment, the climate, and public health. In the face of scientific uncertainty, national and international governments must make decisions on how to proceed. So far, the results have been varied, with some governments banning the process, others enacting moratoria until it is better understood, and others explicitly sanctioning shale gas development. These policies reflect legislature's preferences to avoid false negative errors or false positive ones. Here we argue that policy makers have a prima facie duty to minimize false negatives based on three considerations: (1) protection from serious harm generally takes precedence over the enhancement of welfare; (2) minimizing false negatives in this case is more respectful to people's autonomy; and (3) alternative solutions exist that may provide many of the same benefits while minimizing many of the harms. © 2013.
The efficacy and cost of alternative strategies for systematic screening for type 2 diabetes in the U.S. population 45-74 years of age.

PubMed

Johnson, Susan L; Tabaei, Bahman P; Herman, William H

2005-02-01

To simulate the outcomes of alternative strategies for screening the U.S. population 45-74 years of age for type 2 diabetes. We simulated screening with random plasma glucose (RPG) and cut points of 100, 130, and 160 mg/dl and a multivariate equation including RPG and other variables. Over 15 years, we simulated screening at intervals of 1, 3, and 5 years. All positive screening tests were followed by a diagnostic fasting plasma glucose or an oral glucose tolerance test. Outcomes include the numbers of false-negative, true-positive, and false-positive screening tests and the direct and indirect costs. At year 15, screening every 3 years with an RPG cut point of 100 mg/dl left 0.2 million false negatives, an RPG of 130 mg/dl or the equation left 1.3 million false negatives, and an RPG of 160 mg/dl left 2.8 million false negatives. Over 15 years, the absolute difference between the most sensitive and most specific screening strategy was 4.5 million true positives and 476 million false-positives. Strategies using RPG cut points of 130 mg/dl or the multivariate equation every 3 years identified 17.3 million true positives; however, the equation identified fewer false-positives. The total cost of the most sensitive screening strategy was $42.7 billion and that of the most specific strategy was $6.9 billion. Screening for type 2 diabetes every 3 years with an RPG cut point of 130 mg/dl or the multivariate equation provides good yield and minimizes false-positive screening tests and costs.
Estimating False Positive Contamination in Crater Annotations from Citizen Science Data

NASA Astrophysics Data System (ADS)

Tar, P. D.; Bugiolacchi, R.; Thacker, N. A.; Gilmour, J. D.

2017-01-01

Web-based citizen science often involves the classification of image features by large numbers of minimally trained volunteers, such as the identification of lunar impact craters under the Moon Zoo project. Whilst such approaches facilitate the analysis of large image data sets, the inexperience of users and ambiguity in image content can lead to contamination from false positive identifications. We give an approach, using Linear Poisson Models and image template matching, that can quantify levels of false positive contamination in citizen science Moon Zoo crater annotations. Linear Poisson Models are a form of machine learning which supports predictive error modelling and goodness-of-fits, unlike most alternative machine learning methods. The proposed supervised learning system can reduce the variability in crater counts whilst providing predictive error assessments of estimated quantities of remaining true verses false annotations. In an area of research influenced by human subjectivity, the proposed method provides a level of objectivity through the utilisation of image evidence, guided by candidate crater identifications.
Tricuspid regurgitation by radionuclide angiography and contrast right ventriculography: a preliminary observation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lumia, F.J.; Patil, A.; Germon, P.A.

In a retrospective study correlating the degree of tricuspid regurgitation seen on first-pass radionuclide angiography with that seen on contrast right ventriculography in 51 patients, ten had no tricuspid regurgitation by contrast ventriculography, whereas by radionuclide angiography nine had no regurgitation and one had minimal regurgitation. Of eight patients with minimal tricuspid regurgitation by contrast ventriculography, five had minimal regurgitation by nuclide angiography and three had no regurgitation. Of the 11 patients with mild to moderate tricuspid regurgitation by contrast studies, ten had mild to moderate regurgitation and one had severe regurgitation by nuclide angiography. Of 22 patients with moderatemore » to severe tricuspid regurgitation by contrast studies, 15 had moderate to severe regurgitation and seven had mild to moderate regurgitation by nuclear angiography. In this preliminary study comparing radionuclide angiography with contrast right ventriculography, there were three false-negative and one false-positive nuclide angiograms, giving a sensitivity of 93% and a specificity of 90%.« less
Designing occupancy studies when false-positive detections occur

USGS Publications Warehouse

Clement, Matthew

2016-01-01

1.Recently, estimators have been developed to estimate occupancy probabilities when false-positive detections occur during presence-absence surveys. Some of these estimators combine different types of survey data to improve estimates of occupancy. With these estimators, there is a tradeoff between the number of sample units surveyed, and the number and type of surveys at each sample unit. Guidance on efficient design of studies when false positives occur is unavailable. 2.For a range of scenarios, I identified survey designs that minimized the mean square error of the estimate of occupancy. I considered an approach that uses one survey method and two observation states and an approach that uses two survey methods. For each approach, I used numerical methods to identify optimal survey designs when model assumptions were met and parameter values were correctly anticipated, when parameter values were not correctly anticipated, and when the assumption of no unmodelled detection heterogeneity was violated. 3.Under the approach with two observation states, false positive detections increased the number of recommended surveys, relative to standard occupancy models. If parameter values could not be anticipated, pessimism about detection probabilities avoided poor designs. Detection heterogeneity could require more or fewer repeat surveys, depending on parameter values. If model assumptions were met, the approach with two survey methods was inefficient. However, with poor anticipation of parameter values, with detection heterogeneity, or with removal sampling schemes, combining two survey methods could improve estimates of occupancy. 4.Ignoring false positives can yield biased parameter estimates, yet false positives greatly complicate the design of occupancy studies. Specific guidance for major types of false-positive occupancy models, and for two assumption violations common in field data, can conserve survey resources. This guidance can be used to design efficient monitoring programs and studies of species occurrence, species distribution, or habitat selection, when false positives occur during surveys.
Prediction-Oriented Marker Selection (PROMISE): With Application to High-Dimensional Regression.

PubMed

Kim, Soyeon; Baladandayuthapani, Veerabhadran; Lee, J Jack

2017-06-01

In personalized medicine, biomarkers are used to select therapies with the highest likelihood of success based on an individual patient's biomarker/genomic profile. Two goals are to choose important biomarkers that accurately predict treatment outcomes and to cull unimportant biomarkers to reduce the cost of biological and clinical verifications. These goals are challenging due to the high dimensionality of genomic data. Variable selection methods based on penalized regression (e.g., the lasso and elastic net) have yielded promising results. However, selecting the right amount of penalization is critical to simultaneously achieving these two goals. Standard approaches based on cross-validation (CV) typically provide high prediction accuracy with high true positive rates but at the cost of too many false positives. Alternatively, stability selection (SS) controls the number of false positives, but at the cost of yielding too few true positives. To circumvent these issues, we propose prediction-oriented marker selection (PROMISE), which combines SS with CV to conflate the advantages of both methods. Our application of PROMISE with the lasso and elastic net in data analysis shows that, compared to CV, PROMISE produces sparse solutions, few false positives, and small type I + type II error, and maintains good prediction accuracy, with a marginal decrease in the true positive rates. Compared to SS, PROMISE offers better prediction accuracy and true positive rates. In summary, PROMISE can be applied in many fields to select regularization parameters when the goals are to minimize false positives and maximize prediction accuracy.
Parent Experience With False-Positive Newborn Screening Results for Cystic Fibrosis.

PubMed

Hayeems, Robin Z; Miller, Fiona A; Barg, Carolyn J; Bombard, Yvonne; Kerr, Elizabeth; Tam, Karen; Carroll, June C; Potter, Beth K; Chakraborty, Pranesh; Davies, Christine; Milburn, Jennifer; Patton, Sarah; Bytautas, Jessica P; Taylor, Louise; Price, April; Gonska, Tanja; Keenan, Katherine; Ratjen, Felix; Guttmann, Astrid

2016-09-01

The risk of psychosocial harm in families of infants with false-positive (FP) newborn bloodspot screening (NBS) results for cystic fibrosis (CF) is a longstanding concern. Whether well designed retrieval and confirmatory testing systems can mitigate risks remains unknown. Using a mixed-methods cohort design, we obtained prospective self-report data from mothers of infants with FP CF NBS results 2 to 3 months after confirmatory testing at Ontario's largest follow-up center, and from a randomly selected control sample of mothers of screen negative infants from the same region. Mothers completed a questionnaire assessing experience and psychosocial response. A sample of mothers of FP infants completed qualitative interviews. One hundred thirty-four mothers of FP infants (response rate, 55%) and 411 controls (response rate, 47%) completed questionnaires; 54 mothers of FP infants were interviewed. Selected psychosocial response measures did not detect psychosocial distress in newborns or 1 year later (P > .05). Mothers recalled distress during notification of the positive result and in the follow-up testing period related to fear of chronic illness, but valued the screening system of care in mitigating concerns. Although immediate distress was reported among mothers of FP infants, selected psychometric tools did not detect these concerns. The NBS center from which mothers were recruited minimizes delay between notification and confirmatory testing and ensures trained professionals are communicating results and facilitating follow-up. These factors may explain the presence of minimal psychosocial burden. The screening system reflected herein may be a model for NBS programs working to minimize FP-related psychosocial harm. Copyright © 2016 by the American Academy of Pediatrics.

Utility of minimal preparation ct colonography in detecting colorectal cancer in elderly and frail patients.

PubMed

Meiklejohn, D J; Ridley, L J; Ngu, M C; Cowlishaw, J L; Duller, A; Ridley, W

2018-06-11

Colorectal cancers result in substantial morbidity and mortality to Australian society each year. The usual investigation for bowel malignancyis optical colonoscopy (OC), withcomputed tomographic colonography (CTC) used as an alternative investigation. The catharsis and colon insufflation associated with these investigations pose a higher risk in the elderly and frail. Risks include perforation, serum electrolyte disturbance, and anaesthesia/sedation risks.Minimal preparation computed tomographic colonography (MPCTC) eliminates these risks. This paper audits a 6-year period ofMPCTC in an Australian tertiary referral hospital. 145 patients underwent MPCTC during the study period. There were 7 true positives, 2 false positives and 2 false negatives. Analysis of this population indicates a sensitivity of 0.78 (95% CI 0.51 - 1.05), specificity of 0.99 (95% CI 0.97 - 1.01), positive predictive value (PPV) of 0.78 (95% CI 0.51 - 1.05) and negative predictive value (NPV) of 0.99 (95% CI 0.97 - 1.01). These findings are concordant with other published studies. The auditconfirmsthatminimal preparation CT colonography is a reasonable alternative to OC and CTC in detecting colorectal cancer in symptomatic elderly and frail patients, without the procedural risks inherent inmore invasive investigations. For most patients MPCTC ruled out significant colorectal carcinoma with a high negative predictive value. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.
Accuracy and reliability of forensic latent fingerprint decisions

PubMed Central

Ulery, Bradford T.; Hicklin, R. Austin; Buscaglia, JoAnn; Roberts, Maria Antonia

2011-01-01

The interpretation of forensic fingerprint evidence relies on the expertise of latent print examiners. The National Research Council of the National Academies and the legal and forensic sciences communities have called for research to measure the accuracy and reliability of latent print examiners’ decisions, a challenging and complex problem in need of systematic analysis. Our research is focused on the development of empirical approaches to studying this problem. Here, we report on the first large-scale study of the accuracy and reliability of latent print examiners’ decisions, in which 169 latent print examiners each compared approximately 100 pairs of latent and exemplar fingerprints from a pool of 744 pairs. The fingerprints were selected to include a range of attributes and quality encountered in forensic casework, and to be comparable to searches of an automated fingerprint identification system containing more than 58 million subjects. This study evaluated examiners on key decision points in the fingerprint examination process; procedures used operationally include additional safeguards designed to minimize errors. Five examiners made false positive errors for an overall false positive rate of 0.1%. Eighty-five percent of examiners made at least one false negative error for an overall false negative rate of 7.5%. Independent examination of the same comparisons by different participants (analogous to blind verification) was found to detect all false positive errors and the majority of false negative errors in this study. Examiners frequently differed on whether fingerprints were suitable for reaching a conclusion. PMID:21518906
Accuracy and reliability of forensic latent fingerprint decisions.

PubMed

Ulery, Bradford T; Hicklin, R Austin; Buscaglia, Joann; Roberts, Maria Antonia

2011-05-10

The interpretation of forensic fingerprint evidence relies on the expertise of latent print examiners. The National Research Council of the National Academies and the legal and forensic sciences communities have called for research to measure the accuracy and reliability of latent print examiners' decisions, a challenging and complex problem in need of systematic analysis. Our research is focused on the development of empirical approaches to studying this problem. Here, we report on the first large-scale study of the accuracy and reliability of latent print examiners' decisions, in which 169 latent print examiners each compared approximately 100 pairs of latent and exemplar fingerprints from a pool of 744 pairs. The fingerprints were selected to include a range of attributes and quality encountered in forensic casework, and to be comparable to searches of an automated fingerprint identification system containing more than 58 million subjects. This study evaluated examiners on key decision points in the fingerprint examination process; procedures used operationally include additional safeguards designed to minimize errors. Five examiners made false positive errors for an overall false positive rate of 0.1%. Eighty-five percent of examiners made at least one false negative error for an overall false negative rate of 7.5%. Independent examination of the same comparisons by different participants (analogous to blind verification) was found to detect all false positive errors and the majority of false negative errors in this study. Examiners frequently differed on whether fingerprints were suitable for reaching a conclusion.
Evaluation of the on-site immunoassay drug-screening device Triage-TOX in routine forensic autopsy.

PubMed

Tominaga, Mariko; Michiue, Tomomi; Maeda, Hitoshi

2015-11-01

Instrumental identification of drugs with quantification is essential in forensic toxicology, while on-site immunoassay urinalysis drug-screening devices conveniently provide preliminary information when adequately used. However, suitable or sufficient urine specimens are not always available. The present study evaluated the efficacy of a new on-site immunoassay drug-screening device Triage-TOX (Alere Inc., San Diego, CA, USA), which has recently been developed to provide objective data on the one-step automated processor, using 51 urine and 19 pericardial fluid samples from 66 forensic autopsy cases, compared with Triage-Drug of Abuse (DOA) and Monitect-9. For benzodiazepines, the positive predictive value and specificity of Triage-TOX were higher than those of Triage-DOA; however, sensitivity was higher with Monitect-9, despite frequent false-positives. The results for the other drugs with the three devices also included a few false-negatives and false-positives. These observations indicate the applicability of Triage-TOX in preliminary drug screening using urine or alternative materials in routine forensic autopsy, when a possible false-negative is considered, especially for benzodiazepines, providing objective information; however, the combined use of another device such as Monitect-9 can help minimize misinterpretation prior to instrumental analysis. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.
Screening for colorectal cancer.

PubMed

Ross, C C

1988-12-01

Efforts to decrease the number of deaths from colorectal cancer have focused on screening techniques, since no etiologic agent has been identified. Current screening regimens are designed to detect colorectal cancer in a large population in a cost-efficient manner and to minimize the risks associated with work-ups for false-positive tests. A two-part screening questionnaire for colorectal cancer helps identify patients who are at moderate risk for this cancer.
Variants and pitfalls on radioiodine scans in pediatric patients with differentiated thyroid carcinoma.

PubMed

Mostafa, Mohamed; Vali, Reza; Chan, Jeffrey; Omarkhail, Yusuaf; Shammas, Amer

2016-10-01

Potentially false-positive findings on radioiodine scans in children with differentiated thyroid carcinoma can mimic functioning thyroid tissue and functioning thyroid carcinomatous tissue. Such false-positive findings comprise variants and pitfalls that can vary slightly in children as compared with adults. To determine the patterns and frequency of these potential false-positive findings on radioiodine scans in children with differentiated thyroid carcinoma. We reviewed a total of 223 radioiodine scans from 53 pediatric patients (mean age 13.3 years, 37 girls) with differentiated thyroid carcinoma. Focal or regional activity that likely did not represent functioning thyroid tissue or functioning thyroid carcinomatous tissue were categorized as variants or pitfalls. The final diagnosis was confirmed by reviewing the concurrent and follow-up clinical data, correlative ultrasonography, CT scanning, serum thyroglobulin and antithyroglobulin antibody levels. We calculated the frequency of these variants and pitfalls from diagnostic and post-therapy radioiodine scans. The most common variant on the radioiodine scans was the thymic activity (24/223, 10.8%) followed by the cardiac activity (8/223, 3.6%). Salivary contamination and star artifact, caused by prominent thyroid remnant, were the most important observed pitfalls. Variants and pitfalls that mimic functioning thyroid tissue or functioning thyroid carcinomatous tissue on radioiodine scan in children with differentiated thyroid carcinoma are not infrequent, but they decrease in frequency on successive radioiodine scans. Potential false-positive findings can be minimized with proper knowledge of the common variants and pitfalls in children and correlation with clinical, laboratory and imaging data.
A Customized Attention-Based Long Short-Term Memory Network for Distant Supervised Relation Extraction.

PubMed

He, Dengchao; Zhang, Hongjun; Hao, Wenning; Zhang, Rui; Cheng, Kai

2017-07-01

Distant supervision, a widely applied approach in the field of relation extraction can automatically generate large amounts of labeled training corpus with minimal manual effort. However, the labeled training corpus may have many false-positive data, which would hurt the performance of relation extraction. Moreover, in traditional feature-based distant supervised approaches, extraction models adopt human design features with natural language processing. It may also cause poor performance. To address these two shortcomings, we propose a customized attention-based long short-term memory network. Our approach adopts word-level attention to achieve better data representation for relation extraction without manually designed features to perform distant supervision instead of fully supervised relation extraction, and it utilizes instance-level attention to tackle the problem of false-positive data. Experimental results demonstrate that our proposed approach is effective and achieves better performance than traditional methods.
Validation of missed space-group symmetry in X-ray powder diffraction structures with dispersion-corrected density functional theory.

PubMed

Hempler, Daniela; Schmidt, Martin U; van de Streek, Jacco

2017-08-01

More than 600 molecular crystal structures with correct, incorrect and uncertain space-group symmetry were energy-minimized with dispersion-corrected density functional theory (DFT-D, PBE-D3). For the purpose of determining the correct space-group symmetry the required tolerance on the atomic coordinates of all non-H atoms is established to be 0.2 Å. For 98.5% of 200 molecular crystal structures published with missed symmetry, the correct space group is identified; there are no false positives. Very small, very symmetrical molecules can end up in artificially high space groups upon energy minimization, although this is easily detected through visual inspection. If the space group of a crystal structure determined from powder diffraction data is ambiguous, energy minimization with DFT-D provides a fast and reliable method to select the correct space group.
Efficacy of 67 gallium ECT imaging in lymphoma, infection, and lung carcinoma: A comparison with planar imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harwood, S.J.; Anderson, M.W.; Klein, R.C.

1984-01-01

Emission computed tomography (ECT) studies were performed on a GE 400 A/T camera and ADAC computers (system 3 and system 3300). Thirty-three sets of ECT and planar images were obtained in 20 patients over a six month period. Imaging was performed 48 hours after the intravenous administration of 5 mc of Gallium 67 citrate. No bowel preparation was employed. Comparison is made of the initial nuclear medicine report derived from planar and ECT imaging aided by clinical knowledge versus the consensus opinion of two nuclear medicine physicians reading the planar images along with minimal clinical information. The lymphoma series consistsmore » of 18 scans in 10 patients. There were 5 scans in which a false negative planar interpretation was changed to a true positive ECT interpretation. Sensitivity of planar imaging for lymphoma was 58% which rose to 100% with addition of ECT information. There were no false positives by either technique. There were 5 sets of scans in 5 lung carcinoma patients. Sensitivity of the planar images was 60% because of 2 false negative results. Sensitivity of the ECT technique was 100%. There were no false positives. The infection series consists of 10 scans in 5 patients. Sensitivity of ECT was 100%, sensitivity of planar was 66%. There was 1 false positive planar. For the total series the accuracy of planar imaging was 69% and the predictive value of a negative planar interpretation was 44%. Corresponding values for ECT imaging were 100%. The authors' experience demonstrates significant increase in sensitivity without loss of specificity resulting from the use of Emission Computed Tomography in both chest and abdomen in patients with lymphoma, infection, and lung cancer.« less
Reference intervals for plasma free metanephrines with an age adjustment for normetanephrine for optimized laboratory testing of phaeochromocytoma.

PubMed

Eisenhofer, Graeme; Lattke, Peter; Herberg, Maria; Siegert, Gabriele; Qin, Nan; Därr, Roland; Hoyer, Jana; Villringer, Arno; Prejbisz, Aleksander; Januszewicz, Andrzej; Remaley, Alan; Martucci, Victoria; Pacak, Karel; Ross, H Alec; Sweep, Fred C G J; Lenders, Jacques W M

2013-01-01

Measurements of plasma normetanephrine and metanephrine provide a useful diagnostic test for phaeochromocytoma, but this depends on appropriate reference intervals. Upper cut-offs set too high compromise diagnostic sensitivity, whereas set too low, false-positives are a problem. This study aimed to establish optimal reference intervals for plasma normetanephrine and metanephrine. Blood samples were collected in the supine position from 1226 subjects, aged 5-84 y, including 116 children, 575 normotensive and hypertensive adults and 535 patients in whom phaeochromocytoma was ruled out. Reference intervals were examined according to age and gender. Various models were examined to optimize upper cut-offs according to estimates of diagnostic sensitivity and specificity in a separate validation group of 3888 patients tested for phaeochromocytoma, including 558 with confirmed disease. Plasma metanephrine, but not normetanephrine, was higher (P < 0.001) in men than in women, but reference intervals did not differ. Age showed a positive relationship (P < 0.0001) with plasma normetanephrine and a weaker relationship (P = 0.021) with metanephrine. Upper cut-offs of reference intervals for normetanephrine increased from 0.47 nmol/L in children to 1.05 nmol/L in subjects over 60 y. A curvilinear model for age-adjusted compared with fixed upper cut-offs for normetanephrine, together with a higher cut-off for metanephrine (0.45 versus 0.32 nmol/L), resulted in a substantial gain in diagnostic specificity from 88.3% to 96.0% with minimal loss in diagnostic sensitivity from 93.9% to 93.6%. These data establish age-adjusted cut-offs of reference intervals for plasma normetanephrine and optimized cut-offs for metanephrine useful for minimizing false-positive results.
Reference intervals for plasma free metanephrines with an age adjustment for normetanephrine for optimized laboratory testing of phaeochromocytoma

PubMed Central

Eisenhofer, Graeme; Lattke, Peter; Herberg, Maria; Siegert, Gabriele; Qin, Nan; Därr, Roland; Hoyer, Jana; Villringer, Arno; Prejbisz, Aleksander; Januszewicz, Andrzej; Remaley, Alan; Martucci, Victoria; Pacak, Karel; Ross, H Alec; Sweep, Fred C G J; Lenders, Jacques W M

2016-01-01

Background Measurements of plasma normetanephrine and metanephrine provide a useful diagnostic test for phaeochromocytoma, but this depends on appropriate reference intervals. Upper cut-offs set too high compromise diagnostic sensitivity, whereas set too low, false-positives are a problem. This study aimed to establish optimal reference intervals for plasma normetanephrine and metanephrine. Methods Blood samples were collected in the supine position from 1226 subjects, aged 5–84 y, including 116 children, 575 normotensive and hypertensive adults and 535 patients in whom phaeochromocytoma was ruled out. Reference intervals were examined according to age and gender. Various models were examined to optimize upper cut-offs according to estimates of diagnostic sensitivity and specificity in a separate validation group of 3888 patients tested for phaeochromocytoma, including 558 with confirmed disease. Results Plasma metanephrine, but not normetanephrine, was higher (P < 0.001) in men than in women, but reference intervals did not differ. Age showed a positive relationship (P < 0.0001) with plasma normetanephrine and a weaker relationship (P = 0.021) with metanephrine. Upper cut-offs of reference intervals for normetanephrine increased from 0.47 nmol/L in children to 1.05 nmol/L in subjects over 60 y. A curvilinear model for age-adjusted compared with fixed upper cut-offs for normetanephrine, together with a higher cut-off for metanephrine (0.45 versus 0.32 nmol/L), resulted in a substantial gain in diagnostic specificity from 88.3% to 96.0% with minimal loss in diagnostic sensitivity from 93.9% to 93.6%. Conclusions These data establish age-adjusted cut-offs of reference intervals for plasma normetanephrine and optimized cut-offs for metanephrine useful for minimizing false-positive results. PMID:23065528
Computer-aided marginal artery detection on computed tomographic colonography

NASA Astrophysics Data System (ADS)

Wei, Zhuoshi; Yao, Jianhua; Wang, Shijun; Liu, Jiamin; Summers, Ronald M.

2012-03-01

Computed tomographic colonography (CTC) is a minimally invasive technique for colonic polyps and cancer screening. The marginal artery of the colon, also known as the marginal artery of Drummond, is the blood vessel that connects the inferior mesenteric artery with the superior mesenteric artery. The marginal artery runs parallel to the colon for its entire length, providing the blood supply to the colon. Detecting the marginal artery may benefit computer-aided detection (CAD) of colonic polyp. It can be used to identify teniae coli based on their anatomic spatial relationship. It can also serve as an alternative marker for colon localization, in case of colon collapse and inability to directly compute the endoluminal centerline. This paper proposes an automatic method for marginal artery detection on CTC. To the best of our knowledge, this is the first work presented for this purpose. Our method includes two stages. The first stage extracts the blood vessels in the abdominal region. The eigenvalue of Hessian matrix is used to detect line-like structures in the images. The second stage is to reduce the false positives in the first step. We used two different masks to exclude the false positive vessel regions. One is a dilated colon mask which is obtained by colon segmentation. The other is an eroded visceral fat mask which is obtained by fat segmentation in the abdominal region. We tested our method on a CTC dataset with 6 cases. Using ratio-of-overlap with manual labeling of the marginal artery as the standard-of-reference, our method yielded true positive, false positive and false negative fractions of 89%, 33%, 11%, respectively.
Localized Glaucomatous Change Detection within the Proper Orthogonal Decomposition Framework

PubMed Central

Balasubramanian, Madhusudhanan; Kriegman, David J.; Bowd, Christopher; Holst, Michael; Weinreb, Robert N.; Sample, Pamela A.; Zangwill, Linda M.

2012-01-01

Purpose. To detect localized glaucomatous structural changes using proper orthogonal decomposition (POD) framework with false-positive control that minimizes confirmatory follow-ups, and to compare the results to topographic change analysis (TCA). Methods. We included 167 participants (246 eyes) with ≥4 Heidelberg Retina Tomograph (HRT)-II exams from the Diagnostic Innovations in Glaucoma Study; 36 eyes progressed by stereo-photographs or visual fields. All other patient eyes (n = 210) were non-progressing. Specificities were evaluated using 21 normal eyes. Significance of change at each HRT superpixel between each follow-up and its nearest baseline (obtained using POD) was estimated using mixed-effects ANOVA. Locations with significant reduction in retinal height (red pixels) were determined using Bonferroni, Lehmann-Romano k-family-wise error rate (k-FWER), and Benjamini-Hochberg false discovery rate (FDR) type I error control procedures. Observed positive rate (OPR) in each follow-up was calculated as a ratio of number of red pixels within disk to disk size. Progression by POD was defined as one or more follow-ups with OPR greater than the anticipated false-positive rate. TCA was evaluated using the recently proposed liberal, moderate, and conservative progression criteria. Results. Sensitivity in progressors, specificity in normals, and specificity in non-progressors, respectively, were POD-Bonferroni = 100%, 0%, and 0%; POD k-FWER = 78%, 86%, and 43%; POD-FDR = 78%, 86%, and 43%; POD k-FWER with retinal height change ≥50 μm = 61%, 95%, and 60%; TCA-liberal = 86%, 62%, and 21%; TCA-moderate = 53%, 100%, and 70%; and TCA-conservative = 17%, 100%, and 84%. Conclusions. With a stronger control of type I errors, k-FWER in POD framework minimized confirmatory follow-ups while providing diagnostic accuracy comparable to TCA. Thus, POD with k-FWER shows promise to reduce the number of confirmatory follow-ups required for clinical care and studies evaluating new glaucoma treatments. (ClinicalTrials.gov number, NCT00221897.) PMID:22491406
Detection of insect damage in almonds

NASA Astrophysics Data System (ADS)

Kim, Soowon; Schatzki, Thomas F.

1999-01-01

Pinhole insect damage in natural almonds is very difficult to detect on-line. Further, evidence exists relating insect damage to aflatoxin contamination. Hence, for quality and health reasons, methods to detect and remove such damaged nuts are of great importance in this study, we explored the possibility of using x-ray imaging to detect pinhole damage in almonds by insects. X-ray film images of about 2000 almonds and x-ray linescan images of only 522 pinhole damaged almonds were obtained. The pinhole damaged region appeared slightly darker than non-damaged region in x-ray negative images. A machine recognition algorithm was developed to detect these darker regions. The algorithm used the first order and the second order information to identify the damaged region. To reduce the possibility of false positive results due to germ region in high resolution images, germ detection and removal routines were also included. With film images, the algorithm showed approximately an 81 percent correct recognition ratio with only 1 percent false positives whereas line scan images correctly recognized 65 percent of pinholes with about 9 percent false positives. The algorithms was very fast and efficient requiring only minimal computation time. If implemented on line, theoretical throughput of this recognition system would be 66 nuts/second.
Automated detection of tuberculosis on sputum smeared slides using stepwise classification

NASA Astrophysics Data System (ADS)

Divekar, Ajay; Pangilinan, Corina; Coetzee, Gerrit; Sondh, Tarlochan; Lure, Fleming Y. M.; Kennedy, Sean

2012-03-01

Routine visual slide screening for identification of tuberculosis (TB) bacilli in stained sputum slides under microscope system is a tedious labor-intensive task and can miss up to 50% of TB. Based on the Shannon cofactor expansion on Boolean function for classification, a stepwise classification (SWC) algorithm is developed to remove different types of false positives, one type at a time, and to increase the detection of TB bacilli at different concentrations. Both bacilli and non-bacilli objects are first analyzed and classified into several different categories including scanty positive, high concentration positive, and several non-bacilli categories: small bright objects, beaded, dim elongated objects, etc. The morphological and contrast features are extracted based on aprior clinical knowledge. The SWC is composed of several individual classifiers. Individual classifier to increase the bacilli counts utilizes an adaptive algorithm based on a microbiologist's statistical heuristic decision process. Individual classifier to reduce false positive is developed through minimization from a binary decision tree to classify different types of true and false positive based on feature vectors. Finally, the detection algorithm is was tested on 102 independent confirmed negative and 74 positive cases. A multi-class task analysis shows high accordance rate for negative, scanty, and high-concentration as 88.24%, 56.00%, and 97.96%, respectively. A binary-class task analysis using a receiver operating characteristics method with the area under the curve (Az) is also utilized to analyze the performance of this detection algorithm, showing the superior detection performance on the high-concentration cases (Az=0.913) and cases mixed with high-concentration and scanty cases (Az=0.878).
Assessing environmental DNA detection in controlled lentic systems.

PubMed

Moyer, Gregory R; Díaz-Ferguson, Edgardo; Hill, Jeffrey E; Shea, Colin

2014-01-01

Little consideration has been given to environmental DNA (eDNA) sampling strategies for rare species. The certainty of species detection relies on understanding false positive and false negative error rates. We used artificial ponds together with logistic regression models to assess the detection of African jewelfish eDNA at varying fish densities (0, 0.32, 1.75, and 5.25 fish/m3). Our objectives were to determine the most effective water stratum for eDNA detection, estimate true and false positive eDNA detection rates, and assess the number of water samples necessary to minimize the risk of false negatives. There were 28 eDNA detections in 324, 1-L, water samples collected from four experimental ponds. The best-approximating model indicated that the per-L-sample probability of eDNA detection was 4.86 times more likely for every 2.53 fish/m3 (1 SD) increase in fish density and 1.67 times less likely for every 1.02 C (1 SD) increase in water temperature. The best section of the water column to detect eDNA was the surface and to a lesser extent the bottom. Although no false positives were detected, the estimated likely number of false positives in samples from ponds that contained fish averaged 3.62. At high densities of African jewelfish, 3-5 L of water provided a >95% probability for the presence/absence of its eDNA. Conversely, at moderate and low densities, the number of water samples necessary to achieve a >95% probability of eDNA detection approximated 42-73 and >100 L, respectively. Potential biases associated with incomplete detection of eDNA could be alleviated via formal estimation of eDNA detection probabilities under an occupancy modeling framework; alternatively, the filtration of hundreds of liters of water may be required to achieve a high (e.g., 95%) level of certainty that African jewelfish eDNA will be detected at low densities (i.e., <0.32 fish/m3 or 1.75 g/m3).
Control/display trade-off study for single-pilot instrument flight rule operations

NASA Technical Reports Server (NTRS)

Hoh, R.

1983-01-01

The objectives were to determine minimum autopilot functions and displays required to keep pilot workload at an acceptable level; to determine what constitutes an acceptable level of workload; to identify critical tasks; and to suggest specific experiments required to refine conclusions. It was determined that workload relief is derived from basic stability augmentation; that complex autopilots can lead to serious blunders; and that displays need to enhance positional awareness and minimize the likelihood of false hypothesis.
The specificity of heterophil antibodies in patients and healthy donors with no or minimal signs of infectious mononucleosis.

PubMed

Horwitz, C A; Henle, W; Henle, G; Polesky, H; Wexler, H; Ward, P

1976-01-01

Over several years sera were collected from 14 heterophil-positive students or patients who did not fulfill minimal hematologic criteria for infectious mononucleosis (I.M.) The specificity of these heterophil reactions for I.M. was investigated by determining antibodies to Epstein-Barr virus-determined antigens, i.e., to viral capsid antigens (VCA), early antigens (EA), and EBV-associated nuclear antigens (EBNA). On the basis of detectable anti-EA and/or the early absence and late emergence of anti-EBNA, four of these 14 individuals showed evidence of a current or very recent primary Epstein-Barr virus infection. The other ten patients showed antibody patterns indicative of Epstein-Barr virus infections in the past, and no firm conclusions could be drawn with regard to the specificity of their heterophil reactions. It was assumed, however, that some represented atypical clinical forms of EBV infection and that timing of specimen collection was a factor in explaining the paucity of Downey cells. In three patients, the absorbed heterophil-positive reactions persisted with little change in titer for at least 22 mo and thus might represent false-positive tests.
Prenatal Ultrasound Screening: False Positive Soft Markers May Alter Maternal Representations and Mother-Infant Interaction

PubMed Central

Viaux-Savelon, Sylvie; Dommergues, Marc; Rosenblum, Ouriel; Bodeau, Nicolas; Aidane, Elizabeth; Philippon, Odile; Mazet, Philippe; Vibert-Guigue, Claude; Vauthier-Brouzes, Danièle; Feldman, Ruth; Cohen, David

2012-01-01

Background In up to 5% of pregnancies, ultrasound screening detects a “soft marker” (SM) that places the foetus at risk for a severe abnormality. In most cases, prenatal diagnostic work-up rules out a severe defect. We aimed to study the effects of false positive SM on maternal emotional status, maternal representations of the infant, and mother-infant interaction. Methodology and Principal Findings Utilizing an extreme-case prospective case control design, we selected from a group of 244 women undergoing ultrasound, 19 pregnant women whose foetus had a positive SM screening and a reassuring diagnostic work up, and 19 controls without SM matched for age and education. In the third trimester of pregnancy, within one week after delivery, and 2 months postpartum, we assessed anxiety, depression, and maternal representations. Mother-infant interactions were videotaped during feeding within one week after delivery and again at 2 months postpartum and coded blindly using the Coding Interactive Behavior (CIB) scales. Anxiety and depression scores were significantly higher at all assessment points in the SM group. Maternal representations were also different between SM and control groups at all study time. Perturbations to early mother-infant interactions were observed in the SM group. These dyads showed greater dysregulation, lower maternal sensitivity, higher maternal intrusive behaviour and higher infant avoidance. Multivariate analysis showed that maternal representation and depression at third trimester predicted mother-infant interaction. Conclusion False positive ultrasound screenings for SM are not benign and negatively affect the developing maternal-infant attachment. Medical efforts should be directed to minimize as much as possible such false diagnoses, and to limit their psychological adverse consequences. PMID:22292077
Risk assessment of false-positive quantitative real-time PCR results in food, due to detection of DNA originating from dead cells.

PubMed

Wolffs, Petra; Norling, Börje; Rådström, Peter

2005-03-01

Real-time PCR technology is increasingly used for detection and quantification of pathogens in food samples. A main disadvantage of nucleic acid detection is the inability to distinguish between signals originating from viable cells and DNA released from dead cells. In order to gain knowledge concerning risks of false-positive results due to detection of DNA originating from dead cells, quantitative PCR (qPCR) was used to investigate the degradation kinetics of free DNA in four types of meat samples. Results showed that the fastest degradation rate was observed (1 log unit per 0.5 h) in chicken homogenate, whereas the slowest rate was observed in pork rinse (1 log unit per 120.5 h). Overall results indicated that degradation occurred faster in chicken samples than in pork samples and faster at higher temperatures. Based on these results, it was concluded that, especially in pork samples, there is a risk of false-positive PCR results. This was confirmed in a quantitative study on cell death and signal persistence over a period of 28 days, employing three different methods, i.e. viable counts, direct qPCR, and finally floatation, a recently developed discontinuous density centrifugation method, followed by qPCR. Results showed that direct qPCR resulted in an overestimation of up to 10 times of the amount of cells in the samples compared to viable counts, due to detection of DNA from dead cells. However, after using floatation prior to qPCR, results resembled the viable count data. This indicates that by using of floatation as a sample treatment step prior to qPCR, the risk of false-positive PCR results due to detection of dead cells, can be minimized.

False positives in Biolog EcoPlates™ and MT2 MicroPlates™ caused by calcium.

PubMed

Pierce, Melissa L; Ward, J Evan; Dobbs, Fred C

2014-02-01

Biolog MicroPlates(TM) (e.g. EcoPlate(TM), MT2 MicroPlate(TM), GN MicroPlate(TM)) are useful tools for characterizing microbial communities, providing community-level physiological profiles to terrestrial and aquatic ecologists. The more recently designed Biolog EcoPlates have been used frequently in aquatic ecology with success. This study, however, reveals one major problem when using EcoPlates to evaluate samples within an estuarine or seawater matrix. At concentrations greater than 100 parts per million, the cation calcium begins to interfere with the microplate chemistry, causing false positive readings. Experiments, in which multiple treatments of natural and artificial seawater were tested, as well as calcium-addition experiments, demonstrate that calcium inhibits complete dissolution of the minimal growth medium in wells. Future studies involving Biolog EcoPlates and MicroPlates should take this effect into account, and the dilution of samples is strongly recommended to diminish the "calcium effect." Copyright © 2013 Elsevier B.V. All rights reserved.
Detection of miRNA using a double-strand displacement biosensor with a self-complementary fluorescent reporter.

PubMed

Larkey, Nicholas E; Almlie, C Kyle; Tran, Victoria; Egan, Marianne; Burrows, Sean M

2014-02-04

Design of rapid, selective, and sensitive DNA and ribonucleic acid (RNA) biosensors capable of minimizing false positives from nuclease degradation is crucial for translational research and clinical diagnostics. We present proof-of-principle studies of an innovative micro-ribonucleic acid (miRNA) reporter-probe biosensor that displaces a self-complementary reporter, while target miRNA binds to the probe. The freed reporter folds into a hairpin structure to induce a decrease in the fluorescent signal. The self-complementarity of the reporter facilitates the reduction of false positives from nuclease degradation. Nanomolar limits of detection and quantitation were capable with this proof-of-principle design. Detection of miRNA occurs within 10 min and does not require any additional hybridization, labeling, or rinsing steps. The potential for medical applications of the reporter-probe biosensor is demonstrated by selective detection of a cancer regulating microRNA, Lethal-7 (Let-7a). Mechanisms for transporting the biosensor across the cell membrane will be the focus of future work.
DOE Office of Scientific and Technical Information (OSTI.GOV)

Dana Kelly; Kurt Vedros; Robert Youngblood

This paper examines false indication probabilities in the context of the Mitigating System Performance Index (MSPI), in order to investigate the pros and cons of different approaches to resolving two coupled issues: (1) sensitivity to the prior distribution used in calculating the Bayesian-corrected unreliability contribution to the MSPI, and (2) whether (in a particular plant configuration) to model the fuel oil transfer pump (FOTP) as a separate component, or integrally to its emergency diesel generator (EDG). False indication probabilities were calculated for the following situations: (1) all component reliability parameters at their baseline values, so that the true indication ismore » green, meaning that an indication of white or above would be false positive; (2) one or more components degraded to the extent that the true indication would be (mid) white, and “false” would be green (negative) or yellow (negative) or red (negative). In key respects, this was the approach taken in NUREG-1753. The prior distributions examined were the constrained noninformative (CNI) prior used currently by the MSPI, a mixture of conjugate priors, the Jeffreys noninformative prior, a nonconjugate log(istic)-normal prior, and the minimally informative prior investigated in (Kelly et al., 2010). The mid-white performance state was set at ?CDF = ?10 ? 10-6/yr. For each simulated time history, a check is made of whether the calculated ?CDF is above or below 10-6/yr. If the parameters were at their baseline values, and ?CDF > 10-6/yr, this is counted as a false positive. Conversely, if one or all of the parameters are set to values corresponding to ?CDF > 10-6/yr but that time history’s ?CDF < 10-6/yr, this is counted as a false negative indication. The false indication (positive or negative) probability is then estimated as the number of false positive or negative counts divided by the number of time histories (100,000). Results are presented for a set of base case parameter values, and three sensitivity cases in which the number of FOTP demands was reduced, along with the Birnbaum importance of the FOTP.« less
A critical reappraisal of false negative sentinel lymph node biopsy in melanoma.

PubMed

Manca, G; Romanini, A; Rubello, D; Mazzarri, S; Boni, G; Chiacchio, S; Tredici, M; Duce, V; Tardelli, E; Volterrani, D; Mariani, G

2014-06-01

Lymphatic mapping and sentinel lymph node biopsy (SLNB) have completely changed the clinical management of cutaneous melanoma. This procedure has been accepted worldwide as a recognized method for nodal staging. SLNB is able to accurately determine nodal basin status, providing the most useful prognostic information. However, SLNB is not a perfect diagnostic test. Several large-scale studies have reported a relatively high false-negative rate (5.6-21%), correctly defined as the proportion of false-negative results with respect to the total number of "actual" positive lymph nodes. The main purpose of this review is to address the technical issues that nuclear physicians, surgeons, and pathologists should carefully consider to improve the accuracy of SLNB by minimizing its false-negative rate. In particular, SPECT/CT imaging has demonstrated to be able to identify a greater number of sentinel lymph nodes (SLNs) than those found by planar lymphoscintigraphy. Furthermore, a unique definition in the international guidelines is missing for the operational identification of SLNs, which may be partly responsible for this relatively high false-negative rate of SLNB. Therefore, it is recommended for the scientific community to agree on the radioactive counting rate threshold so that the surgeon can be better radioguided to detect all the lymph nodes which are most likely to harbor metastases. Another possible source of error may be linked to the examination of the harvested SLNs by conventional histopathological methods. A more careful and extensive SLN analysis (e.g. molecular analysis by RT-PCR) is able to find more positive nodes, so that the false-negative rate is reduced. Older age at diagnosis, deeper lesions, histologic ulceration, head-neck anatomical location of primary lesions are the clinical factors associated with false-negative SLNBs in melanoma patients. There is still much controversy about the clinical significance of a false-negative SLNB on the prognosis of melanoma patients. Indeed, most studies have failed to show that there is worse melanoma-specific survival for false-negative compared to true-positive SLNB patients.
Enhanced HTS hit selection via a local hit rate analysis.

PubMed

Posner, Bruce A; Xi, Hualin; Mills, James E J

2009-10-01

The postprocessing of high-throughput screening (HTS) results is complicated by the occurrence of false positives (inactive compounds misidentified as active by the primary screen) and false negatives (active compounds misidentified as inactive by the primary screen). An activity cutoff is frequently used to select "active" compounds from HTS data; however, this approach is insensitive to both false positives and false negatives. An alternative method that can minimize the occurrence of these artifacts will increase the efficiency of hit selection and therefore lead discovery. In this work, rather than merely using the activity of a given compound, we look at the presence and absence of activity among all compounds in its "chemical space neighborhood" to give a degree of confidence in its activity. We demonstrate that this local hit rate (LHR) analysis method outperforms hit selection based on ranking by primary screen activity values across ten diverse high throughput screens, spanning both cell-based and biochemical assay formats of varying biology and robustness. On average, the local hit rate analysis method was approximately 2.3-fold and approximately 1.3-fold more effective in identifying active compounds and active chemical series, respectively, than selection based on primary activity alone. Moreover, when applied to finding false negatives, this method was 2.3-fold better than ranking by primary activity alone. In most cases, novel hit series were identified that would have otherwise been missed. Additional uses of and observations regarding this HTS analysis approach are also discussed.
Neural correlates of consciousness in patients who have emerged from a minimally conscious state: a cross-sectional multimodal imaging study.

PubMed

Di Perri, Carol; Bahri, Mohamed Ali; Amico, Enrico; Thibaut, Aurore; Heine, Lizette; Antonopoulos, Georgios; Charland-Verville, Vanessa; Wannez, Sarah; Gomez, Francisco; Hustinx, Roland; Tshibanda, Luaba; Demertzi, Athena; Soddu, Andrea; Laureys, Steven

2016-07-01

Between pathologically impaired consciousness and normal consciousness exists a scarcely researched transition zone, referred to as emergence from minimally conscious state, in which patients regain the capacity for functional communication, object use, or both. We investigated neural correlates of consciousness in these patients compared with patients with disorders of consciousness and healthy controls, by multimodal imaging. In this cross-sectional, multimodal imaging study, patients with unresponsive wakefulness syndrome, patients in a minimally conscious state, and patients who had emerged from a minimally conscious state, diagnosed with the Coma Recovery Scale-Revised, were recruited from the neurology department of the Centre Hospitalier Universitaire de Liège, Belgium. Key exclusion criteria were neuroimaging examination in an acute state, sedation or anaesthesia during scanning, large focal brain damage, motion parameters of more than 3 mm in translation and 3° in rotation, and suboptimal segmentation and normalisation. We acquired resting state functional and structural MRI data and (18)F-fluorodeoxyglucose (FDG) PET data; we used seed-based functional MRI (fMRI) analysis to investigate positive default mode network connectivity (within-network correlations) and negative default mode network connectivity (between-network anticorrelations). We correlated FDG-PET brain metabolism with fMRI connectivity. We used voxel-based morphometry to test the effect of anatomical deformations on functional connectivity. We recruited a convenience sample of 58 patients (21 [36%] with unresponsive wakefulness syndrome, 24 [41%] in a minimally conscious state, and 13 [22%] who had emerged from a minimally conscious state) and 35 healthy controls between Oct 1, 2009, and Oct 31, 2014. We detected consciousness-level-dependent increases (from unresponsive wakefulness syndrome, minimally conscious state, emergence from minimally conscious state, to healthy controls) for positive and negative default mode network connectivity, brain metabolism, and grey matter volume (p<0·05 false discovery rate corrected for multiple comparisons). Positive default mode network connectivity differed between patients and controls but not among patient groups (F test p<0·0001). Negative default mode network connectivity was only detected in healthy controls and in those who had emerged from a minimally conscious state; patients with unresponsive wakefulness syndrome or in a minimally conscious state showed pathological between-network positive connectivity (hyperconnectivity; F test p<0·0001). Brain metabolism correlated with positive default mode network connectivity (Spearman's r=0·50 [95% CI 0·26 to 0·61]; p<0·0001) and negative default mode network connectivity (Spearman's r=-0·52 [-0·35 to -0·67); p<0·0001). Grey matter volume did not differ between the studied groups (F test p=0·06). Partial preservation of between-network anticorrelations, which are seemingly of neuronal origin and cannot be solely explained by morphological deformations, characterise patients who have emerged from a minimally conscious state. Conversely, patients with disorders of consciousness show pathological between-network correlations. Apart from a deeper understanding of the neural correlates of consciousness, these findings have clinical implications and might be particularly relevant for outcome prediction and could inspire new therapeutic options. Belgian National Funds for Scientific Research (FNRS), European Commission, Natural Sciences and Engineering Research Council of Canada, James McDonnell Foundation, European Space Agency, Mind Science Foundation, French Speaking Community Concerted Research Action, Fondazione Europea di Ricerca Biomedica, University and University Hospital of Liège (Liège, Belgium), and University of Western Ontario (London, ON, Canada). Copyright © 2016 Elsevier Ltd. All rights reserved.
Missing value imputation strategies for metabolomics data.

PubMed

Armitage, Emily Grace; Godzien, Joanna; Alonso-Herranz, Vanesa; López-Gonzálvez, Ángeles; Barbas, Coral

2015-12-01

The origin of missing values can be caused by different reasons and depending on these origins missing values should be considered differently and dealt with in different ways. In this research, four methods of imputation have been compared with respect to revealing their effects on the normality and variance of data, on statistical significance and on the approximation of a suitable threshold to accept missing data as truly missing. Additionally, the effects of different strategies for controlling familywise error rate or false discovery and how they work with the different strategies for missing value imputation have been evaluated. Missing values were found to affect normality and variance of data and k-means nearest neighbour imputation was the best method tested for restoring this. Bonferroni correction was the best method for maximizing true positives and minimizing false positives and it was observed that as low as 40% missing data could be truly missing. The range between 40 and 70% missing values was defined as a "gray area" and therefore a strategy has been proposed that provides a balance between the optimal imputation strategy that was k-means nearest neighbor and the best approximation of positioning real zeros. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
An extension of the receiver operating characteristic curve and AUC-optimal classification.

PubMed

Takenouchi, Takashi; Komori, Osamu; Eguchi, Shinto

2012-10-01

While most proposed methods for solving classification problems focus on minimization of the classification error rate, we are interested in the receiver operating characteristic (ROC) curve, which provides more information about classification performance than the error rate does. The area under the ROC curve (AUC) is a natural measure for overall assessment of a classifier based on the ROC curve. We discuss a class of concave functions for AUC maximization in which a boosting-type algorithm including RankBoost is considered, and the Bayesian risk consistency and the lower bound of the optimum function are discussed. A procedure derived by maximizing a specific optimum function has high robustness, based on gross error sensitivity. Additionally, we focus on the partial AUC, which is the partial area under the ROC curve. For example, in medical screening, a high true-positive rate to the fixed lower false-positive rate is preferable and thus the partial AUC corresponding to lower false-positive rates is much more important than the remaining AUC. We extend the class of concave optimum functions for partial AUC optimality with the boosting algorithm. We investigated the validity of the proposed method through several experiments with data sets in the UCI repository.
Automated EEG entropy measurements in coma, vegetative state/unresponsive wakefulness syndrome and minimally conscious state

PubMed Central

Gosseries, Olivia; Schnakers, Caroline; Ledoux, Didier; Vanhaudenhuyse, Audrey; Bruno, Marie-Aurélie; Demertzi, Athéna; Noirhomme, Quentin; Lehembre, Rémy; Damas, Pierre; Goldman, Serge; Peeters, Erika; Moonen, Gustave; Laureys, Steven

Summary Monitoring the level of consciousness in brain-injured patients with disorders of consciousness is crucial as it provides diagnostic and prognostic information. Behavioral assessment remains the gold standard for assessing consciousness but previous studies have shown a high rate of misdiagnosis. This study aimed to investigate the usefulness of electroencephalography (EEG) entropy measurements in differentiating unconscious (coma or vegetative) from minimally conscious patients. Left fronto-temporal EEG recordings (10-minute resting state epochs) were prospectively obtained in 56 patients and 16 age-matched healthy volunteers. Patients were assessed in the acute (≤1 month post-injury; n=29) or chronic (>1 month post-injury; n=27) stage. The etiology was traumatic in 23 patients. Automated online EEG entropy calculations (providing an arbitrary value ranging from 0 to 91) were compared with behavioral assessments (Coma Recovery Scale-Revised) and outcome. EEG entropy correlated with Coma Recovery Scale total scores (r=0.49). Mean EEG entropy values were higher in minimally conscious (73±19; mean and standard deviation) than in vegetative/unresponsive wakefulness syndrome patients (45±28). Receiver operating characteristic analysis revealed an entropy cut-off value of 52 differentiating acute unconscious from minimally conscious patients (sensitivity 89% and specificity 90%). In chronic patients, entropy measurements offered no reliable diagnostic information. EEG entropy measurements did not allow prediction of outcome. User-independent time-frequency balanced spectral EEG entropy measurements seem to constitute an interesting diagnostic – albeit not prognostic – tool for assessing neural network complexity in disorders of consciousness in the acute setting. Future studies are needed before using this tool in routine clinical practice, and these should seek to improve automated EEG quantification paradigms in order to reduce the remaining false negative and false positive findings. PMID:21693085
Calculation and evaluation of sediment effect concentrations for the amphipod Hyalella azteca and the midge Chironomus riparius

USGS Publications Warehouse

Ingersoll, Christopher G.; Haverland, Pamela S.; Brunson, Eric L.; Canfield, Timothy J.; Dwyer, F. James; Henke, Chris; Kemble, Nile E.; Mount, David R.; Fox, Richard G.

1996-01-01

Procedures are described for calculating and evaluating sediment effect concentrations (SECs) using laboratory data on the toxicity of contaminants associated with field-collected sediment to the amphipod Hyalella azteca and the midge Chironomus riparius. SECs are defined as the concentrations of individual contaminants in sediment below which toxicity is rarely observed and above which toxicity is frequently observed. The objective of the present study was to develop SECs to classify toxicity data for Great Lake sediment samples tested with Hyalella azteca and Chironomus riparius. This SEC database included samples from additional sites across the United States in order to make the database as robust as possible. Three types of SECs were calculated from these data: (1) Effect Range Low (ERL) and Effect Range Median (ERM), (2) Threshold Effect Level (TEL) and Probable Effect Level (PEL), and (3) No Effect Concentration (NEC). We were able to calculate SECs primarily for total metals, simultaneously extracted metals, polychlorinated biphenyls (PCBs), and polycyclic aromatic hydrocarbons (PAHs). The ranges of concentrations in sediment were too narrow in our database to adequately evaluate SECs for butyltins, methyl mercury, polychlorinated dioxins and furans, or chlorinated pesticides. About 60 to 80% of the sediment samples in the database are correctly classified as toxic or not toxic depending on type of SEC evaluated. ERMs and ERLs are generally as reliable as paired PELs and TELs at classifying both toxic and non-toxic samples in our database. Reliability of the SECs in terms of correctly classifying sediment samples is similar between ERMs and NECs; however, ERMs minimize Type I error (false positives) relative to ERLs and minimize Type II error (false negatives) relative to NECs. Correct classification of samples can be improved by using only the most reliable individual SECs for chemicals (i.e., those with a higher percentage of correct classification). SECs calculated using sediment concentrations normalized to total organic carbon (TOC) concentrations did not improve the reliability compared to SECs calculated using dry-weight concentrations. The range of TOC concentrations in our database was relatively narrow compared to the ranges of contaminant concentrations. Therefore, normalizing dry-weight concentrations to a relatively narrow range of TOC concentrations had little influence on relative concentra of contaminants among samples. When SECs are used to conduct a preliminary screening to predict the potential for toxicity in the absence of actual toxicity testing, a low number of SEC exceedances should be used to minimize the potential for false negatives; however, the risk of accepting higher false positives is increased.
One or two serological assay testing strategy for diagnosis of HBV and HCV infection? The use of predictive modelling.

PubMed

Parry, John V; Easterbrook, Philippa; Sands, Anita R

2017-11-01

Initial serological testing for chronic hepatitis B virus (HBV) and hepatitis C virus (HCV) infection is conducted using either rapid diagnostic tests (RDT) or laboratory-based enzyme immunoassays (EIA)s for detection of hepatitis B surface antigen (HBsAg) or antibodies to HCV (anti-HCV), typically on serum or plasma specimens and, for certain RDTs, capillary whole blood. WHO recommends the use of standardized testing strategies - defined as a sequence of one or more assays to maximize testing accuracy while simplifying the testing process and ideally minimizing cost. Our objective was to examine the diagnostic outcomes of a one- versus two-assay serological testing strategy. These data were used to inform recommendations in the 2017 WHO Guidelines on hepatitis B and C testing. Few published studies have compared diagnostic outcomes for one-assay versus two-assay serological testing strategies for HBsAg and anti-HCV. Therefore, the principles of Bayesian statistics were used to conduct a modelling exercise to examine the outcomes of a one-assay versus two-assay testing strategy when applied to a hypothetical population of 10,000 individuals. The resulting model examined the diagnostic outcomes (true and false positive diagnoses; true and false negative diagnoses; positive and negative predictive values as a function of prevalence; and total tests required) for both one-assay and two-assay testing strategies. The performance characteristics assumed for assays used within the testing strategies were informed by WHO prequalification assessment findings and systematic reviews for diagnostic accuracy studies. Each of the presumptive testing strategies (one-assay or two-assay) was modelled at varying prevalences of HBsAg (10%, 2% and 0.4%) and of anti-HCV (40%, 10%, 2% and 0.4%), aimed at representing the range of testing populations typically encountered in WHO Member States. When the two-assay testing strategy was considered, the model assumed the independence of the two assays. Modeling demonstrated that applying a single assay (HBsAg or anti-HCV), even with high specificity (99%), may result in considerable numbers of false positive diagnoses and low positive predictive values (PPV), particularly in lower prevalence settings. Even at very low prevalences shifting to a two-assay testing strategy would result in a PPV approaching 1.0. When test sensitivity is high (>99%) false negative reactions are rare at all but the highest prevalences; but a two-test strategy might yield more false negative diagnoses. The order in which the tests are used has no impact on the overall accuracy of a two-assay strategy though it may impact the total number of tests needed to complete the diagnostic strategy, incurring added cost and complexity. HBsAg assays may have a low sensitivity (<90%), and result in large numbers of false negative diagnoses, particularly in high prevalence settings, which would be exacerbated in the two-assay testing strategy. In contrast, most anti-HCV assays have high sensitivity and lead to fewer false negative results, both in the one-assay and two-assay testing strategies. At prevalences ≤2% the number of tests needed using a second assay was nearly always small, at <300 per 10,000 individuals tested, making sustainability of a second assay uncertain in such a setting. A key public health objective of an effective testing strategy is to identify all individuals who would benefit from treatment. Therefore, a strategy that prioritizes a high NPV (minimal false negatives) may be acceptable even if the PPV is suboptimal (some false positives) as the implementation of such a public health programme must also take account of other factors such as costs, feasibility, impact on testing uptake and linkage to care, and consequences of a false-positive test. This rationale informed the development of the WHO Viral Hepatitis Testing Guidelines, with a conditional recommendation for a one-assay serological testing strategy in most testing settings and populations (≥0.4% prevalence in population tested). A one-test strategy results in few failures to diagnose infection and, although it is associated under most assumptions with a sub-optimal PPV, benefits include greater simplicity, easier implementation, lower costs and better feasibility, uptake and linkage to care. Furthermore, prior to antiviral therapy all those diagnosed either HBsAg or anti-HCV positive will require confirmation of viræmia, preventing unnecessary treatment of those who may be false positive on serology. For HBsAg, in low-prevalence settings (≤0.4%), a second recommendation was made to consider a two-assay testing strategy, using a confirmatory neutralization step or a second different HBsAg assay.
Hyperedge bundling: A practical solution to spurious interactions in MEG/EEG source connectivity analyses.

PubMed

Wang, Sheng H; Lobier, Muriel; Siebenhühner, Felix; Puoliväli, Tuomas; Palva, Satu; Palva, J Matias

2018-06-01

Inter-areal functional connectivity (FC), neuronal synchronization in particular, is thought to constitute a key systems-level mechanism for coordination of neuronal processing and communication between brain regions. Evidence to support this hypothesis has been gained largely using invasive electrophysiological approaches. In humans, neuronal activity can be non-invasively recorded only with magneto- and electroencephalography (MEG/EEG), which have been used to assess FC networks with high temporal resolution and whole-scalp coverage. However, even in source-reconstructed MEG/EEG data, signal mixing, or "source leakage", is a significant confounder for FC analyses and network localization. Signal mixing leads to two distinct kinds of false-positive observations: artificial interactions (AI) caused directly by mixing and spurious interactions (SI) arising indirectly from the spread of signals from true interacting sources to nearby false loci. To date, several interaction metrics have been developed to solve the AI problem, but the SI problem has remained largely intractable in MEG/EEG all-to-all source connectivity studies. Here, we advance a novel approach for correcting SIs in FC analyses using source-reconstructed MEG/EEG data. Our approach is to bundle observed FC connections into hyperedges by their adjacency in signal mixing. Using realistic simulations, we show here that bundling yields hyperedges with good separability of true positives and little loss in the true positive rate. Hyperedge bundling thus significantly decreases graph noise by minimizing the false-positive to true-positive ratio. Finally, we demonstrate the advantage of edge bundling in the visualization of large-scale cortical networks with real MEG data. We propose that hypergraphs yielded by bundling represent well the set of true cortical interactions that are detectable and dissociable in MEG/EEG connectivity analysis. Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.
Improving and Assessing Planet Sensitivity of the GPI Exoplanet Survey with a Forward Model Matched Filter

NASA Astrophysics Data System (ADS)

Ruffio, Jean-Baptiste; Macintosh, Bruce; Wang, Jason J.; Pueyo, Laurent; Nielsen, Eric L.; De Rosa, Robert J.; Czekala, Ian; Marley, Mark S.; Arriaga, Pauline; Bailey, Vanessa P.; Barman, Travis; Bulger, Joanna; Chilcote, Jeffrey; Cotten, Tara; Doyon, Rene; Duchêne, Gaspard; Fitzgerald, Michael P.; Follette, Katherine B.; Gerard, Benjamin L.; Goodsell, Stephen J.; Graham, James R.; Greenbaum, Alexandra Z.; Hibon, Pascale; Hung, Li-Wei; Ingraham, Patrick; Kalas, Paul; Konopacky, Quinn; Larkin, James E.; Maire, Jérôme; Marchis, Franck; Marois, Christian; Metchev, Stanimir; Millar-Blanchaer, Maxwell A.; Morzinski, Katie M.; Oppenheimer, Rebecca; Palmer, David; Patience, Jennifer; Perrin, Marshall; Poyneer, Lisa; Rajan, Abhijith; Rameau, Julien; Rantakyrö, Fredrik T.; Savransky, Dmitry; Schneider, Adam C.; Sivaramakrishnan, Anand; Song, Inseok; Soummer, Remi; Thomas, Sandrine; Wallace, J. Kent; Ward-Duong, Kimberly; Wiktorowicz, Sloane; Wolff, Schuyler

2017-06-01

We present a new matched-filter algorithm for direct detection of point sources in the immediate vicinity of bright stars. The stellar point-spread function (PSF) is first subtracted using a Karhunen-Loéve image processing (KLIP) algorithm with angular and spectral differential imaging (ADI and SDI). The KLIP-induced distortion of the astrophysical signal is included in the matched-filter template by computing a forward model of the PSF at every position in the image. To optimize the performance of the algorithm, we conduct extensive planet injection and recovery tests and tune the exoplanet spectra template and KLIP reduction aggressiveness to maximize the signal-to-noise ratio (S/N) of the recovered planets. We show that only two spectral templates are necessary to recover any young Jovian exoplanets with minimal S/N loss. We also developed a complete pipeline for the automated detection of point-source candidates, the calculation of receiver operating characteristics (ROC), contrast curves based on false positives, and completeness contours. We process in a uniform manner more than 330 data sets from the Gemini Planet Imager Exoplanet Survey and assess GPI typical sensitivity as a function of the star and the hypothetical companion spectral type. This work allows for the first time a comparison of different detection algorithms at a survey scale accounting for both planet completeness and false-positive rate. We show that the new forward model matched filter allows the detection of 50% fainter objects than a conventional cross-correlation technique with a Gaussian PSF template for the same false-positive rate.
Sentinel lymph node mapping in melanoma: the issue of false-negative findings.

PubMed

Manca, Gianpiero; Rubello, Domenico; Romanini, Antonella; Boni, Giuseppe; Chiacchio, Serena; Tredici, Manuel; Mazzarri, Sara; Duce, Valerio; Colletti, Patrick M; Volterrani, Duccio; Mariani, Giuliano

2014-07-01

Management of cutaneous melanoma has changed after introduction in the clinical routine of sentinel lymph node biopsy (SLNB) for nodal staging. By defining the nodal basin status, SLNB provides a powerful prognostic information. Nevertheless, some debate still surrounds the accuracy of this procedure in terms of false-negative rate. Several large-scale studies have reported a relatively high false-negative rate (5.6%-21%), correctly defined as the proportion of false-negative results with respect to the total number of "actual" positive lymph nodes. In this review, we identified all the technical aspects that the nuclear medicine physician, the surgeon, and the pathologist should take into account to improve accuracy of the procedure and minimize the false-negative rate. In particular, SPECT/CT imaging detects more SLNs than those found by planar lymphoscintigraphy. Furthermore, the nuclear medicine community should reach a consensus on the radioactive counting rate threshold to better guide the surgeon in identifying the lymph nodes with the highest likelihood of housing metastases ("true biologic SLNs"). Analysis of the harvested SLNs by conventional techniques is also a further potential source for error. More accurate SLN analysis (eg, molecular analysis by reverse transcriptase-polymerase chain reaction) and more extensive SLN sampling identify more positive nodes, thus reducing the false-negative rate.The clinical factors identifying patients at higher-risk local recurrence after a negative SLNB include older age at diagnosis, deeper lesions, histological ulceration, and head-neck anatomic location of the primary lesion.The clinical impact of a false-negative SLNB on the prognosis of melanoma patients remains controversial, because the majority of studies have failed to demonstrate overall statistically significant disadvantage in melanoma-specific survival for false-negative SLNB patients compared with true-positive SLNB patients.When new more effective drugs will be available in the adjuvant setting for stage III melanoma patients, the implication of an accurate staging procedure for the sentinel lymph nodes will be crucial for both patients and clinicians. Standardization and accuracy of SLN identification, removal, and analysis are required.
Prevalence and associated risk factors of latent tuberculosis infection among undergraduate and postgraduate dental students: A retrospective study.

PubMed

Lamberti, Monica; Muoio, Maria Rosaria; Westermann, Claudia; Nienhaus, Albert; Arnese, Antonio; Ribeiro Sobrinho, Antônio Paulino; Di Giuseppe, Gabriella; Garzillo, Elpidio Maria; Crispino, Vincenzo; Coppola, Nicola; De Rosa, Alfredo

2017-03-04

To estimate the prevalence of latent tuberculosis (TB) infection (LTBI) in Italian dental students exposed to the same occupational risks as dental health care personnel and to evaluate potential risk factors, a cross-sectional study was conducted on undergraduate and postgraduate students. After clinical evaluation, students were given a tuberculin skin test; in those found positive, an interferon-γ release assay (IGRA) was conducted. Of the 281 students enrolled, 10 were only TST positive; 8 were TST or/and IGRA positive. We found that participants testing positive at TST and/or IGRA, a group in which the risk of false LTBI positives is minimal, were older and had been studying longer. Although the prevalence of LTBI among dental students in our study was low, a risk of acquiring a work-related infection exists even in a country with a low incidence of TB. Thus, dental students should be screened to catch LTBI early on.
Eclipsing Binaries From the CSTAR Project at Dome A, Antarctica

NASA Astrophysics Data System (ADS)

Yang, Ming; Zhang, Hui; Wang, Songhu; Zhou, Ji-Lin; Zhou, Xu; Wang, Lingzhi; Wang, Lifan; Wittenmyer, R. A.; Liu, Hui-Gen; Meng, Zeyang; Ashley, M. C. B.; Storey, J. W. V.; Bayliss, D.; Tinney, Chris; Wang, Ying; Wu, Donghong; Liang, Ensi; Yu, Zhouyi; Fan, Zhou; Feng, Long-Long; Gong, Xuefei; Lawrence, J. S.; Liu, Qiang; Luong-Van, D. M.; Ma, Jun; Wu, Zhenyu; Yan, Jun; Yang, Huigen; Yang, Ji; Yuan, Xiangyan; Zhang, Tianmeng; Zhu, Zhenxi; Zou, Hu

2015-04-01

The Chinese Small Telescope ARray (CSTAR) has observed an area around the Celestial South Pole at Dome A since 2008. About 20,000 light curves in the i band were obtained during the observation season lasting from 2008 March to July. The photometric precision achieves about 4 mmag at i = 7.5 and 20 mmag at i = 12 within a 30 s exposure time. These light curves are analyzed using Lomb-Scargle, Phase Dispersion Minimization, and Box Least Squares methods to search for periodic signals. False positives may appear as a variable signature caused by contaminating stars and the observation mode of CSTAR. Therefore, the period and position of each variable candidate are checked to eliminate false positives. Eclipsing binaries are removed by visual inspection, frequency spectrum analysis, and a locally linear embedding technique. We identify 53 eclipsing binaries in the field of view of CSTAR, containing 24 detached binaries, 8 semi-detached binaries, 18 contact binaries, and 3 ellipsoidal variables. To derive the parameters of these binaries, we use the Eclipsing Binaries via Artificial Intelligence method. The primary and secondary eclipse timing variations (ETVs) for semi-detached and contact systems are analyzed. Correlated primary and secondary ETVs confirmed by false alarm tests may indicate an unseen perturbing companion. Through ETV analysis, we identify two triple systems (CSTAR J084612.64-883342.9 and CSTAR J220502.55-895206.7). The orbital parameters of the third body in CSTAR J220502.55-895206.7 are derived using a simple dynamical model.
Level of visual acuity necessary to avoid false-positives on the HRR and Ishihara color vision tests.

PubMed

Ng, Jason S; Shih, Brian

2017-05-11

Minimizing false-positives (FPs) when evaluating color vision is important in eye care. Identification of plate 1 (demonstration plate) is often considered a way to avoid FPs. However, few studies have quantified the minimum level of visual acuity (VA) that would minimize FPs for the Ishihara and HRR color tests. Threshold levels of optical defocus were obtained from 25 color normal subjects. Blur levels were obtained for Ishihara (38 plate) plates 1, 10, and 15 and 4th edition HRR plates 1, 7, 10, and 20 using the method of limits. Corresponding VAs were measured through these blur levels at 40 centimeters after adjusting for the dioptric distance difference. Analysis of variance testing was used to analyze the data. Mean optical defocus values in diopters (mean ± SD) for HRR plates 1, 7, 10, and 20 were 6.23 ± 1.61, 1.23 ± 1.16, 2.41 ± 1.31, and 7.96 ± 2.03, respectively, and for Ishihara plates 1, 10, and 15 were 5.70 ± 1.52, 3.68 ± 1.71, and 4.62 ± 1.56, respectively. There was a significant difference between the screening and demonstration plates for both tests (p<0.001). Based on the plate in each test that was found to be the least tolerant to blur, the average minimum VAs needed to identify the screening plates were approximately 20/180 for the Ishihara test and 20/50 for the HRR test. Identifying the demonstration plate in the Ishihara and HRR tests does not ensure FPs will be avoided.
Testing the effectiveness of automated acoustic sensors for monitoring vocal activity of Marbled Murrelets Brachyramphus marmoratus

USGS Publications Warehouse

Cragg, Jenna L.; Burger, Alan E.; Piatt, John F.

2015-01-01

Cryptic nest sites and secretive breeding behavior make population estimates and monitoring of Marbled Murrelets Brachyramphus marmoratus difficult and expensive. Standard audio-visual and radar protocols have been refined but require intensive field time by trained personnel. We examined the detection range of automated sound recorders (Song Meters; Wildlife Acoustics Inc.) and the reliability of automated recognition models (“recognizers”) for identifying and quantifying Marbled Murrelet vocalizations during the 2011 and 2012 breeding seasons at Kodiak Island, Alaska. The detection range of murrelet calls by Song Meters was estimated to be 60 m. Recognizers detected 20 632 murrelet calls (keer and keheer) from a sample of 268 h of recordings, yielding 5 870 call series, which compared favorably with human scanning of spectrograms (on average detecting 95% of the number of call series identified by a human observer, but not necessarily the same call series). The false-negative rate (percentage of murrelet call series that the recognizers failed to detect) was 32%, mainly involving weak calls and short call series. False-positives (other sounds included by recognizers as murrelet calls) were primarily due to complex songs of other bird species, wind and rain. False-positives were lower in forest nesting habitat (48%) and highest in shrubby vegetation where calls of other birds were common (97%–99%). Acoustic recorders tracked spatial and seasonal trends in vocal activity, with higher call detections in high-quality forested habitat and during late July/early August. Automated acoustic monitoring of Marbled Murrelet calls could provide cost-effective, valuable information for assessing habitat use and temporal and spatial trends in nesting activity; reliability is dependent on careful placement of sensors to minimize false-positives and on prudent application of digital recognizers with visual checking of spectrograms.
Real-time people and vehicle detection from UAV imagery

NASA Astrophysics Data System (ADS)

Gaszczak, Anna; Breckon, Toby P.; Han, Jiwan

2011-01-01

A generic and robust approach for the real-time detection of people and vehicles from an Unmanned Aerial Vehicle (UAV) is an important goal within the framework of fully autonomous UAV deployment for aerial reconnaissance and surveillance. Here we present an approach for the automatic detection of vehicles based on using multiple trained cascaded Haar classifiers with secondary confirmation in thermal imagery. Additionally we present a related approach for people detection in thermal imagery based on a similar cascaded classification technique combining additional multivariate Gaussian shape matching. The results presented show the successful detection of vehicle and people under varying conditions in both isolated rural and cluttered urban environments with minimal false positive detection. Performance of the detector is optimized to reduce the overall false positive rate by aiming at the detection of each object of interest (vehicle/person) at least once in the environment (i.e. per search patter flight path) rather than every object in each image frame. Currently the detection rate for people is ~70% and cars ~80% although the overall episodic object detection rate for each flight pattern exceeds 90%.
Analysis of Hypodermic Needles and Syringes for the Presence of Blood and Polydimethylsiloxane (Silicone) Utilizing Microchemical Tests and Infrared Spectroscopy.

PubMed

Crowe, John B; Lanzarotta, Adam; Witkowski, Mark R; Andria, Sara E

2015-07-01

Suspect hypodermic needles and syringes were seized from an unlicensed individual who was allegedly injecting patients with silicone (polydimethylsiloxane [PDMS]) for cosmetic enhancement. Since control syringe barrels and needles often contain an interfering PDMS lubricant, a risk for false positives of foreign PDMS exists. The focus of this report was to minimize this risk and determine a quick and reliable test for the presence of blood in PDMS matrices. Using ATR-FT-IR spectroscopy, the risk for false-positive identification of foreign PDMS was reduced by (i) overfilling the sampling aperture to prevent spectral distortions and (ii) sampling a region of the suspect syringe/needle assembly where manufacturer-applied PDMS is not typically located. Analysis for blood indicated that the Teichman microchemical test was effective for detecting blood in the presence of PDMS. Overall, detecting PDMS established intent and detecting blood established that the needle containing the PDMS had been used for injection. Published 2015. This article is a U.S. Government work and is in the public domain in the USA.

Minimally invasive management of hepatic cysts: indications and complications.

PubMed

Vardakostas, D; Damaskos, C; Garmpis, N; Antoniou, E A; Kontzoglou, K; Kouraklis, G; Dimitroulis, D

2018-03-01

Liver cysts are divided into congenital and acquired. Congenital cystic lesions include polycystic liver disease, simple cysts, duct related and ciliated hepatic foregut cysts. Acquired cystic lesions are divided into infectious and non-infectious. The infectious cysts are the hydatid cyst, the amoebic abscess, and the pyogenic abscess, whereas the non-infectious cysts are neoplastic cysts and false cysts. While modern medicine provides a lot of minimally invasive therapeutic modalities, there has emerged a pressing need for understanding the various types of liver cysts, the possible minimal therapeutic options along with their indications and complications. We aim is to clarify the role of minimally invasive techniques in the management of hepatic cysts. A literature review was performed using the MEDLINE database. The search terms were: liver cyst, minimally invasive, laparoscopic, percutaneous, drainage and fenestration. We reviewed 82 English language publications articles, published until October 2017. Minimally invasive management of liver LC is an emerging field including many therapeutic modalities ranging from the percutaneous aspiration of pyogenic abscesses to laparoscopic hepatectomy for hepatic cystadenomas. The most used techniques are percutaneous drainage, laparoscopic fenestration, and laparoscopic hepatectomy. The application of the various minimally invasive approaches, as well as their indication and complications, depend on the type of the cystic lesion, its size and its position in the liver. Percutaneous drainage is mostly used in simple cysts, hydatid cysts, pyogenic abscesses and bilomas. Laparoscopic fenestration is mostly used in simple cysts and polycystic liver disease. Finally, laparoscopic hepatectomy is mostly used in polycystic liver disease, hydatid cysts, and cystadenomas.
Performance of Spectrogram-Based Seizure Identification of Adult EEGs by Critical Care Nurses and Neurophysiologists.

PubMed

Amorim, Edilberto; Williamson, Craig A; Moura, Lidia M V R; Shafi, Mouhsin M; Gaspard, Nicolas; Rosenthal, Eric S; Guanci, Mary M; Rajajee, Venkatakrishna; Westover, M Brandon

2017-07-01

Continuous EEG screening using spectrograms or compressed spectral arrays (CSAs) by neurophysiologists has shorter review times with minimal loss of sensitivity for seizure detection when compared with visual analysis of raw EEG. Limited data are available on the performance characteristics of CSA-based seizure detection by neurocritical care nurses. This is a prospective cross-sectional study that was conducted in two academic neurocritical care units and involved 33 neurointensive care unit nurses and four neurophysiologists. All nurses underwent a brief training session before testing. Forty two-hour CSA segments of continuous EEG were reviewed and rated for the presence of seizures. Two experienced clinical neurophysiologists masked to the CSA data performed conventional visual analysis of the raw EEG and served as the gold standard. The overall accuracy was 55.7% among nurses and 67.5% among neurophysiologists. Nurse seizure detection sensitivity was 73.8%, and the false-positive rate was 1-per-3.2 hours. Sensitivity and false-alarm rate for the neurophysiologists was 66.3% and 1-per-6.4 hours, respectively. Interrater agreement for seizure screening was fair for nurses (Gwet AC1 statistic: 43.4%) and neurophysiologists (AC1: 46.3%). Training nurses to perform seizure screening utilizing continuous EEG CSA displays is feasible and associated with moderate sensitivity. Nurses and neurophysiologists had comparable sensitivities, but nurses had a higher false-positive rate. Further work is needed to improve sensitivity and reduce false-alarm rates.
Improving and Assessing Planet Sensitivity of the GPI Exoplanet Survey with a Forward Model Matched Filter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ruffio, Jean-Baptiste; Macintosh, Bruce; Nielsen, Eric L.

We present a new matched-filter algorithm for direct detection of point sources in the immediate vicinity of bright stars. The stellar point-spread function (PSF) is first subtracted using a Karhunen-Loéve image processing (KLIP) algorithm with angular and spectral differential imaging (ADI and SDI). The KLIP-induced distortion of the astrophysical signal is included in the matched-filter template by computing a forward model of the PSF at every position in the image. To optimize the performance of the algorithm, we conduct extensive planet injection and recovery tests and tune the exoplanet spectra template and KLIP reduction aggressiveness to maximize the signal-to-noise ratiomore » (S/N) of the recovered planets. We show that only two spectral templates are necessary to recover any young Jovian exoplanets with minimal S/N loss. We also developed a complete pipeline for the automated detection of point-source candidates, the calculation of receiver operating characteristics (ROC), contrast curves based on false positives, and completeness contours. We process in a uniform manner more than 330 data sets from the Gemini Planet Imager Exoplanet Survey and assess GPI typical sensitivity as a function of the star and the hypothetical companion spectral type. This work allows for the first time a comparison of different detection algorithms at a survey scale accounting for both planet completeness and false-positive rate. We show that the new forward model matched filter allows the detection of 50% fainter objects than a conventional cross-correlation technique with a Gaussian PSF template for the same false-positive rate.« less
Can imaging criteria distinguish enchondroma from grade 1 chondrosarcoma?

PubMed

Crim, Julia; Schmidt, Robert; Layfield, Lester; Hanrahan, Christopher; Manaster, Betty Jean

2015-11-01

To minimize systematic bias and optimize agreement on imaging criteria in order to better define the accuracy of imaging criteria in the diagnosis of grade 1 chondrosarcoma. Study was IRB-approved and HIPAA compliant; informed consent was waived. Records were reviewed and disclosed 53 cases (38 women, 15 men ages 21-76) which were diagnosed as enchondroma or grade 1 chondrosarcoma and had available radiographs, contrast-enhanced MRI, and definitive diagnosis by histology or 5-year follow-up. 2 MSK radiologists read the studies independently after a session where they agreed on criteria for malignancy. Interobserver variability was determined as raw variability and with the kappa statistic. Accuracy was determined compared to final diagnosis. Reliability of imaging features of chondrosarcoma was determined using regression analysis. The correct diagnosis of enchondroma was made on radiographs in 43 (67.2%) of readings, and on MRI in 37/64 (57.8%). The correct diagnosis of chondrosarcoma was made on radiographs in 5/24 (20.8%) of readings, and on MRI in 14/24 (57.8%). A diagnosis of borderline lesion was made in 19/64 (29.7%) of enchondromas on radiographs and 18/64 (28.1%) on MRI. The false positive rate of radiographs for chondrosarcoma was 2/64 (3.1%) and the false positive rate of MRI was 9/64 (14.1%). There was substantial interobserver variability. Cortical thickening and bone expansion were rare but specific signs of chondrosarcoma. Both radiographs and MRI have limitations in the evaluation of low-grade cartilage lesions. MRI has an increased rate of both true-positive and false-positive diagnosis compared to radiographs. Differences in the findings of this study compared to previous literature may reflect the influence of systematic biases. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.
Clinically relevant hypoglycemia prediction metrics for event mitigation.

PubMed

Harvey, Rebecca A; Dassau, Eyal; Zisser, Howard C; Bevier, Wendy; Seborg, Dale E; Jovanovič, Lois; Doyle, Francis J

2012-08-01

The purpose of this study was to develop a method to compare hypoglycemia prediction algorithms and choose parameter settings for different applications, such as triggering insulin pump suspension or alerting for rescue carbohydrate treatment. Hypoglycemia prediction algorithms with different parameter settings were implemented on an ambulatory dataset containing 490 days from 30 subjects with type 1 diabetes mellitus using the Dexcom™ (San Diego, CA) SEVEN™ continuous glucose monitoring system. The performance was evaluated using a proposed set of metrics representing the true-positive ratio, false-positive rate, and distribution of warning times. A prospective, in silico study was performed to show the effect of using different parameter settings to prevent or rescue from hypoglycemia. The retrospective study results suggest the parameter settings for different methods of hypoglycemia mitigation. When rescue carbohydrates are used, a high true-positive ratio, a minimal false-positive rate, and alarms with short warning time are desired. These objectives were met with a 30-min prediction horizon and two successive flags required to alarm: 78% of events were detected with 3.0 false alarms/day and 66% probability of alarms occurring within 30 min of the event. This parameter setting selection was confirmed in silico: treating with rescue carbohydrates reduced the duration of hypoglycemia from 14.9% to 0.5%. However, for a different method, such as pump suspension, this parameter setting only reduced hypoglycemia to 8.7%, as can be expected by the low probability of alarming more than 30 min ahead. The proposed metrics allow direct comparison of hypoglycemia prediction algorithms and selection of parameter settings for different types of hypoglycemia mitigation, as shown in the prospective in silico study in which hypoglycemia was alerted or treated with rescue carbohydrates.
Implementation of Emergency Medical Text Classifier for Syndromic Surveillance

PubMed Central

Travers, Debbie; Haas, Stephanie W.; Waller, Anna E.; Schwartz, Todd A.; Mostafa, Javed; Best, Nakia C.; Crouch, John

2013-01-01

Public health officials use syndromic surveillance systems to facilitate early detection and response to infectious disease outbreaks. Emergency department clinical notes are becoming more available for surveillance but present the challenge of accurately extracting concepts from these text data. The purpose of this study was to implement a new system, Emergency Medical Text Classifier (EMT-C), into daily production for syndromic surveillance and evaluate system performance and user satisfaction. The system was designed to meet user preferences for a syndromic classifier that maximized positive predictive value and minimized false positives in order to provide a manageable workload. EMT-C performed better than the baseline system on all metrics and users were slightly more satisfied with it. It is vital to obtain user input and test new systems in the production environment. PMID:24551413
Implementation of Emergency Medical Text Classifier for syndromic surveillance.

PubMed

Travers, Debbie; Haas, Stephanie W; Waller, Anna E; Schwartz, Todd A; Mostafa, Javed; Best, Nakia C; Crouch, John

2013-01-01

Public health officials use syndromic surveillance systems to facilitate early detection and response to infectious disease outbreaks. Emergency department clinical notes are becoming more available for surveillance but present the challenge of accurately extracting concepts from these text data. The purpose of this study was to implement a new system, Emergency Medical Text Classifier (EMT-C), into daily production for syndromic surveillance and evaluate system performance and user satisfaction. The system was designed to meet user preferences for a syndromic classifier that maximized positive predictive value and minimized false positives in order to provide a manageable workload. EMT-C performed better than the baseline system on all metrics and users were slightly more satisfied with it. It is vital to obtain user input and test new systems in the production environment.
40 CFR 262.27 - Waste minimization certification.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 26 2011-07-01 2011-07-01 false Waste minimization certification. 262.27 Section 262.27 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES (CONTINUED) STANDARDS APPLICABLE TO GENERATORS OF HAZARDOUS WASTE The Manifest § 262.27 Waste minimization...
40 CFR 262.27 - Waste minimization certification.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 27 2012-07-01 2012-07-01 false Waste minimization certification. 262.27 Section 262.27 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES (CONTINUED) STANDARDS APPLICABLE TO GENERATORS OF HAZARDOUS WASTE The Manifest § 262.27 Waste minimization...
40 CFR 262.27 - Waste minimization certification.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 25 2010-07-01 2010-07-01 false Waste minimization certification. 262.27 Section 262.27 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES (CONTINUED) STANDARDS APPLICABLE TO GENERATORS OF HAZARDOUS WASTE The Manifest § 262.27 Waste minimization...
40 CFR 262.27 - Waste minimization certification.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 27 2013-07-01 2013-07-01 false Waste minimization certification. 262.27 Section 262.27 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES (CONTINUED) STANDARDS APPLICABLE TO GENERATORS OF HAZARDOUS WASTE The Manifest § 262.27 Waste minimization...
40 CFR 262.27 - Waste minimization certification.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 26 2014-07-01 2014-07-01 false Waste minimization certification. 262.27 Section 262.27 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES (CONTINUED) STANDARDS APPLICABLE TO GENERATORS OF HAZARDOUS WASTE The Manifest § 262.27 Waste minimization...
A Decision Theoretic Approach to Evaluate Radiation Detection Algorithms

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nobles, Mallory A.; Sego, Landon H.; Cooley, Scott K.

2013-07-01

There are a variety of sensor systems deployed at U.S. border crossings and ports of entry that scan for illicit nuclear material. In this work, we develop a framework for comparing the performance of detection algorithms that interpret the output of these scans and determine when secondary screening is needed. We optimize each algorithm to minimize its risk, or expected loss. We measure an algorithm’s risk by considering its performance over a sample, the probability distribution of threat sources, and the consequence of detection errors. While it is common to optimize algorithms by fixing one error rate and minimizing another,more » our framework allows one to simultaneously consider multiple types of detection errors. Our framework is flexible and easily adapted to many different assumptions regarding the probability of a vehicle containing illicit material, and the relative consequences of a false positive and false negative errors. Our methods can therefore inform decision makers of the algorithm family and parameter values which best reduce the threat from illicit nuclear material, given their understanding of the environment at any point in time. To illustrate the applicability of our methods, in this paper, we compare the risk from two families of detection algorithms and discuss the policy implications of our results.« less
10 CFR 20.1406 - Minimization of contamination.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 1 2010-01-01 2010-01-01 false Minimization of contamination. 20.1406 Section 20.1406 Energy NUCLEAR REGULATORY COMMISSION STANDARDS FOR PROTECTION AGAINST RADIATION Radiological Criteria for License Termination § 20.1406 Minimization of contamination. (a) Applicants for licenses, other than early...
10 CFR 20.1406 - Minimization of contamination.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 1 2011-01-01 2011-01-01 false Minimization of contamination. 20.1406 Section 20.1406 Energy NUCLEAR REGULATORY COMMISSION STANDARDS FOR PROTECTION AGAINST RADIATION Radiological Criteria for License Termination § 20.1406 Minimization of contamination. (a) Applicants for licenses, other than early...
Finite mixture modeling for vehicle crash data with application to hotspot identification.

PubMed

Park, Byung-Jung; Lord, Dominique; Lee, Chungwon

2014-10-01

The application of finite mixture regression models has recently gained an interest from highway safety researchers because of its considerable potential for addressing unobserved heterogeneity. Finite mixture models assume that the observations of a sample arise from two or more unobserved components with unknown proportions. Both fixed and varying weight parameter models have been shown to be useful for explaining the heterogeneity and the nature of the dispersion in crash data. Given the superior performance of the finite mixture model, this study, using observed and simulated data, investigated the relative performance of the finite mixture model and the traditional negative binomial (NB) model in terms of hotspot identification. For the observed data, rural multilane segment crash data for divided highways in California and Texas were used. The results showed that the difference measured by the percentage deviation in ranking orders was relatively small for this dataset. Nevertheless, the ranking results from the finite mixture model were considered more reliable than the NB model because of the better model specification. This finding was also supported by the simulation study which produced a high number of false positives and negatives when a mis-specified model was used for hotspot identification. Regarding an optimal threshold value for identifying hotspots, another simulation analysis indicated that there is a discrepancy between false discovery (increasing) and false negative rates (decreasing). Since the costs associated with false positives and false negatives are different, it is suggested that the selected optimal threshold value should be decided by considering the trade-offs between these two costs so that unnecessary expenses are minimized. Copyright © 2014 Elsevier Ltd. All rights reserved.
Evaluating methods of correcting for multiple comparisons implemented in SPM12 in social neuroscience fMRI studies: an example from moral psychology.

PubMed

Han, Hyemin; Glenn, Andrea L

2018-06-01

In fMRI research, the goal of correcting for multiple comparisons is to identify areas of activity that reflect true effects, and thus would be expected to replicate in future studies. Finding an appropriate balance between trying to minimize false positives (Type I error) while not being too stringent and omitting true effects (Type II error) can be challenging. Furthermore, the advantages and disadvantages of these types of errors may differ for different areas of study. In many areas of social neuroscience that involve complex processes and considerable individual differences, such as the study of moral judgment, effects are typically smaller and statistical power weaker, leading to the suggestion that less stringent corrections that allow for more sensitivity may be beneficial and also result in more false positives. Using moral judgment fMRI data, we evaluated four commonly used methods for multiple comparison correction implemented in Statistical Parametric Mapping 12 by examining which method produced the most precise overlap with results from a meta-analysis of relevant studies and with results from nonparametric permutation analyses. We found that voxelwise thresholding with familywise error correction based on Random Field Theory provides a more precise overlap (i.e., without omitting too few regions or encompassing too many additional regions) than either clusterwise thresholding, Bonferroni correction, or false discovery rate correction methods.
Do the benefits outweigh the side effects of colorectal cancer surveillance? A systematic review.

PubMed

Augestad, Knut Magne; Rose, Johnie; Crawshaw, Benjamin; Cooper, Gregory; Delaney, Conor

2014-05-15

Most patients treated with curative intent for colorectal cancer (CRC) are included in a follow-up program involving periodic evaluations. The survival benefits of a follow-up program are well delineated, and previous meta-analyses have suggested an overall survival improvement of 5%-10% by intensive follow-up. However, in a recent randomized trial, there was no survival benefit when a minimal vs an intensive follow-up program was compared. Less is known about the potential side effects of follow-up. Well-known side effects of preventive programs are those of somatic complications caused by testing, negative psychological consequences of follow-up itself, and the downstream impact of false positive or false negative tests. Accordingly, the potential survival benefits of CRC follow-up must be weighed against these potential negatives. The present review compares the benefits and side effects of CRC follow-up, and we propose future areas for research.
Contrast-enhanced Spectral Mammography: Modality-Specific Artifacts and Other Factors Which May Interfere with Image Quality.

PubMed

Bhimani, Chandni; Li, Luna; Liao, Lydia; Roth, Robyn G; Tinney, Elizabeth; Germaine, Pauline

2017-01-01

Contrast-enhanced spectral mammography (CESM) uses full field digital mammography with the added benefit of intravenous contrast administration to significantly reduce false-positive and false-negative results and improve specificity while maintaining high sensitivity. For CESM to fulfill its purpose, one should be aware of possible artifacts and other factors which may interfere with image quality, and attention should be taken to minimize these factors. This pictorial demonstration will depict types of artifacts detected and other factors that interfere with image acquisition in our practice since CESM implementation. Many of the artifacts and other factors we have encountered while using CESM have simple solutions to resolve them. The illustrated artifacts and other factors interfering with image quality will serve as a useful reference to anyone using CESM. Copyright Â© 2017 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved.
Forensic child sexual abuse evaluations: assessing subjectivity and bias in professional judgements.

PubMed

Everson, Mark D; Sandoval, Jose Miguel

2011-04-01

Evaluators examining the same evidence often arrive at substantially different conclusions in forensic assessments of child sexual abuse (CSA). This study attempts to identify and quantify subjective factors that contribute to such disagreements so that interventions can be devised to improve the reliability of case decisions. Participants included 1106 professionals in the field of child maltreatment representing a range of professional positions or job titles and years of experience. Each completed the Child Forensic Attitude Scale (CFAS), a 28-item survey assessing 3 forensic attitudes believed to influence professional judgments about CSA allegations: emphasis-on-sensitivity (i.e., a focus on minimizing false negatives or errors of undercalling abuse); emphasis-on-specificity (i.e., a focus on minimizing false positives or errors of overcalling abuse); and skepticism toward child and adolescent reports of CSA. A subset of 605 professionals also participated in 1 of 3 diverse decision exercises to assess the influence of the 3 forensic attitudes on ratings of case credibility. Exploratory factor analysis identified 4 factors or attitude subscales that corresponded closely with the original CFAS scales: 2 subscales for emphasis-on-sensitivity and 1 each for emphasis-on-specificity and skepticism. Attitude subscale scores differed significantly by sample source (in-state trainings vs. national conferences), gender, years of experience, and professional position, with Child Protective Service workers unexpectedly more concerned about overcalling abuse and more skeptical of child disclosures than other professionals-a pattern of scores associated with an increased probability of disbelieving CSA allegations. The 3 decision exercises offered validation of the attitude subscales as predictors of professional ratings of case credibility, with adjusted R(2)s for the three exercises ranging from .06 to .24, suggesting highly variable effect sizes. Evaluator disagreements about CSA allegations can be explained, in part, by individual differences in 3 attitudes related to forensic decision-making: emphasis-on-sensitivity, emphasis-on-specificity, and skepticism toward child reports of abuse. These attitudes operate as predispositions or biases toward viewing CSA allegations as likely true or likely false. Several strategies for curbing the influence of subjective factors are highlighted including self-awareness of personal biases and team approaches to assessment. Copyright © 2011 Elsevier Ltd. All rights reserved.

Disease prevalence and the index of detectability: a survey of studies of lung cancer detection by chest radiography

NASA Astrophysics Data System (ADS)

Kundel, Harold L.

2000-04-01

A survey of 12 studies of lung cancer detection with cancer prevalence ranging from 0.9 to 476 cancers per 1000 showed that the unit-slope index of detectability, d', decreased from a high value of 3.9 at low prevalence to 1.4 at high prevalence. A proposed explanation is that the readers are operating on an ROC curve with a slope that is less than unity approximating 0.6. On such a curve, a shift to more stringent criteria that occurs with decreasing prevalence in order to minimize false positives, would result in a increased unity- slope d'.
Spread of the Rat Lungworm (Angiostrongylus cantonensis) in Giant African Land Snails (Lissachatina fulica) in Florida, USA.

PubMed

Iwanowicz, Deborah D; Sanders, Lakyn R; Schill, W Bane; Xayavong, Maniphet V; da Silva, Alexandre J; Qvarnstrom, Yvonne; Smith, Trevor

2015-07-01

The rat lungworm (Angiostrongylus cantonensis) is a parasitic nematode that causes rat lungworm disease. It is the leading cause of eosinophilic meningitis and is a zoonotic health risk. We confirmed the presence of A. cantonensis using species-specific, quantitative PCR in 18 of 50 (36%) giant African land snails (Lissachatina fulica) collected from Miami, Florida, US in May 2013. These snails were collected from seven of 21 core areas that the Florida Department of Agriculture and Consumer Services monitor weekly. Rat lungworms have not previously been identified in these areas. Duplicate DNA extractions of foot muscle tissue from each snail were tested. Of the seven core areas we examined, six were positive for A. cantonensis and prevalence of infection ranged from 27% to 100%. Of the 18 positive snails, only five were positive in both extractions. Our results confirm an increase in the range and prevalence of rat lungworm infection in Miami. We also emphasize the importance of extracting sufficient host tissue to minimize false negatives.
Spread of the Rat Lungworm (Angiostrongylus cantonensis) in Giant African Land Snails (Lissachatina fulica) in Florida, USA

USGS Publications Warehouse

Iwanowicz, Deborah; Sanders, Lakyn R.; Schill, W. Bane; Xayavong, Maniphet V; da Silva, Alexandre J; Qvarnstrom, Yvonne; Smith, Trevor

2015-01-01

The rat lungworm (Angiostrongylus cantonensis) is a parasitic nematode that causes rat lungworm disease. It is the leading cause of eosinophilic meningitis and is a zoonotic health risk. We confirmed the presence of A. cantonensis using species-specific, quantitative PCR in 18 of 50 (36%) giant African land snails (Lissachatina fulica) collected from Miami, Florida in May 2013. These snails were collected from seven of 21 core areas that the Florida Department of Agriculture and Consumer Services monitor weekly. Rat lungworms have not previously been identified in these areas. Duplicate DNA extractions of foot muscle tissue from each snail were tested. Of the seven core areas we examined, six were positive for A. cantonensis and prevalence of infection ranged from 27% to 100%. Of the 18 positive snails, only five were positive in both extractions. Our results confirm an increase in the range and prevalence of rat lungworm infection in Miami. We also emphasize the importance of extracting sufficient host tissue to minimize false negatives.
Automated detection of breast cancer in false-negative screening MRI studies from women at increased risk.

PubMed

Gubern-Mérida, Albert; Vreemann, Suzan; Martí, Robert; Melendez, Jaime; Lardenoije, Susanne; Mann, Ritse M; Karssemeijer, Nico; Platel, Bram

2016-02-01

To evaluate the performance of an automated computer-aided detection (CAD) system to detect breast cancers that were overlooked or misinterpreted in a breast MRI screening program for women at increased risk. We identified 40 patients that were diagnosed with breast cancer in MRI and had a prior MRI examination reported as negative available. In these prior examinations, 24 lesions could retrospectively be identified by two breast radiologists in consensus: 11 were scored as visible and 13 as minimally visible. Additionally, 120 normal scans were collected from 120 women without history of breast cancer or breast surgery participating in the same MRI screening program. A fully automated CAD system was applied to this dataset to detect malignant lesions. At 4 false-positives per normal case, the sensitivity for the detection of cancer lesions that were visible or minimally visible in retrospect in prior-negative examinations was 0.71 (95% CI=0.38-1.00) and 0.31 (0.07-0.59), respectively. A substantial proportion of cancers that were misinterpreted or overlooked in an MRI screening program was detected by a CAD system in prior-negative examinations. It has to be clarified with further studies if such a CAD system has an influence on the number of misinterpreted and overlooked cancers in clinical practice when results are given to a radiologist. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.
7 CFR Appendix B to Part 220 - Categories of Foods of Minimal Nutritional Value

Code of Federal Regulations, 2014 CFR

2014-01-01

... to Part 220—Categories of Foods of Minimal Nutritional Value. (c) Appendix B remains in effect... 7 Agriculture 4 2014-01-01 2014-01-01 false Categories of Foods of Minimal Nutritional Value B Appendix B to Part 220 Agriculture Regulations of the Department of Agriculture (Continued) FOOD AND...
12 CFR 264b.5 - Gifts of more than minimal value.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 12 Banks and Banking 3 2010-01-01 2010-01-01 false Gifts of more than minimal value. 264b.5 Section 264b.5 Banks and Banking FEDERAL RESERVE SYSTEM (CONTINUED) BOARD OF GOVERNORS OF THE FEDERAL... entirely outside the United States (such as transportation, food, and lodging) of more than minimal value...
Enhancement in sample collection for the detection of MDMA using a novel planar SPME (PSPME) device coupled to ion mobility spectrometry (IMS).

PubMed

Gura, Sigalit; Guerra-Diaz, Patricia; Lai, Hanh; Almirall, José R

2009-07-01

Trace detection of illicit drugs challenges the scientific community to develop improved sensitivity and selectivity in sampling and detection techniques. Ion mobility spectrometry (IMS) is one of the prominent trace detectors for illicit drugs and explosives, mostly due to its portability, high sensitivity and fast analysis. Current sampling methods for IMS rely on wiping suspected surfaces or withdrawing air through filters to collect particulates. These methods depend greatly on the particulates being bound onto surfaces or having sufficient vapour pressure to be airborne. Many of these compounds are not readily available in the headspace due to their low vapour pressure. This research presents a novel SPME device for enhanced air sampling and shows the use of optimized IMS by genetic algorithms to target volatile markers and/or odour signatures of illicit substances. The sampling method was based on unique static samplers, planar substrates coated with sol-gel polydimethyl siloxane (PDMS) nanoparticles, also known as planar solid-phase microextraction (PSPME). Due to its surface chemistry, high surface area and capacity, PSPME provides significant increases in sensitivity over conventional fibre SPME. The results show a 50-400 times increase in the detection capacity for piperonal, the odour signature of 3,4-methylenedioxymethamphetamine (MDMA). The PSPME-IMS technique was able to detect 600 ng of piperonal in a 30 s extraction from a quart-sized can containing 5 MDMA tablets, while detection using fibre SPME-IMS was not attainable. In a blind study of six cases suspected to contain varying amounts of MDMA in the tablets, PSPME-IMS successfully detected five positive cases and also produced no false positives or false negatives. One positive case had minimal amounts of MDMA resulting in a false negative response for fibre SPME-IMS.
False Position, Double False Position and Cramer's Rule

ERIC Educational Resources Information Center

Boman, Eugene

2009-01-01

We state and prove the methods of False Position (Regula Falsa) and Double False Position (Regula Duorum Falsorum). The history of both is traced from ancient Egypt and China through the work of Fibonacci, ending with a connection between Double False Position and Cramer's Rule.
Mammography screening using independent double reading with consensus: is there a potential benefit for computer-aided detection?

PubMed

Skaane, Per; Kshirsagar, Ashwini; Hofvind, Solveig; Jahr, Gunnar; Castellino, Ronald A

2012-04-01

Double reading improves the cancer detection rate in mammography screening. Single reading with computer-aided detection (CAD) has been considered to be an alternative to double reading. Little is known about the potential benefit of CAD in breast cancer screening with double reading. To compare prospective independent double reading of screen-film (SFM) and full-field digital (FFDM) mammography in population-based screening with retrospective standalone CAD performance on the baseline mammograms of the screen-detected cancers and subsequent cancers diagnosed during the follow-up period. The study had ethics committee approval. A 5-point rating scale for probability of cancer was used for 23,923 (SFM = 16,983; FFDM = 6940) screening mammograms. Of 208 evaluable cancers, 104 were screen-detected and 104 were subsequent (44 interval and 60 next screening round) cancers. Baseline mammograms of subsequent cancers were retrospectively classified in consensus without information about cancer location, histology, or CAD prompting as normal, non-specific minimal signs, significant minimal signs, and false-negatives. The baseline mammograms of the screen-detected cancers and subsequent cancers were evaluated by CAD. Significant minimal signs and false-negatives were considered 'actionable' and potentially diagnosable if correctly prompted by CAD. CAD correctly marked 94% (98/104) of the baseline mammograms of the screen-detected cancers (SFM = 95% [61/64]; FFDM = 93% [37/40]), including 96% (23/24) of those with discordant interpretations. Considering only those baseline examinations of subsequent cancers prospectively interpreted as normal and retrospectively categorized as 'actionable', CAD input at baseline screening had the potential to increase the cancer detection rate from 0.43% to 0.51% (P = 0.13); and to increase cancer detection by 16% ([104 + 17]/104) and decrease interval cancers by 20% (from 44 to 35). CAD may have the potential to increase cancer detection by up to 16%, and to reduce the number of interval cancers by up to 20% in SFM and FFDM screening programs using independent double reading with consensus review. The influence of true- and false-positive CAD marks on decision-making can, however, only be evaluated in a prospective clinical study.
A two-hypothesis approach to establishing a life detection/biohazard protocol for planetary samples

NASA Astrophysics Data System (ADS)

Conley, Catharine; Steele, Andrew

2016-07-01

The COSPAR policy on performing a biohazard assessment on samples brought from Mars to Earth is framed in the context of a concern for false-positive results. However, as noted during the 2012 Workshop for Life Detection in Samples from Mars (ref. Kminek et al., 2014), a more significant concern for planetary samples brought to Earth is false-negative results, because an undetected biohazard could increase risk to the Earth. This is the reason that stringent contamination control must be a high priority for all Category V Restricted Earth Return missions. A useful conceptual framework for addressing these concerns involves two complementary 'null' hypotheses: testing both of them, together, would allow statistical and community confidence to be developed regarding one or the other conclusion. As noted above, false negatives are of primary concern for safety of the Earth, so the 'Earth Safety null hypothesis' -- that must be disproved to assure low risk to the Earth from samples introduced by Category V Restricted Earth Return missions -- is 'There is native life in these samples.' False positives are of primary concern for Astrobiology, so the 'Astrobiology null hypothesis' -- that must be disproved in order to demonstrate the existence of extraterrestrial life is 'There is no life in these samples.' The presence of Earth contamination would render both of these hypotheses more difficult to disprove. Both these hypotheses can be tested following a strict science protocol; analyse, interprete, test the hypotheses and repeat. The science measurements undertaken are then done in an iterative fashion that responds to discovery with both hypotheses testable from interpretation of the scientific data. This is a robust, community involved activity that ensures maximum science return with minimal sample use.
Combined use of reverse transcriptase polymerase chain reaction and flow cytometry to study minimal residual disease in Philadelphia positive acute lymphoblastic leukemia.

PubMed

Muñoz, L; López, O; Martino, R; Brunet, S; Bellido, M; Rubiol, E; Sierra, J; Nomdedéu, J F

2000-07-01

The Philadelphia chromosome in acute lymphoblastic leukemia (Ph+ ALL) is associated with a poor prognosis given the high frequency of chemoresistance and leukemia relapse. Minimal residual disease (MRD) detection before cytogenetic and hematologic relapse could be useful in early therapy. The most suitable methods for detecting MRD in Ph+ ALL are flow cytometry (FC) and reverse transcriptase polymerase chain reaction (RT-PCR). However, since both techniques carry the risk of false-negative results the combined use of these two techniques could overcome this problem. We report our experience using this approach in 47 bone marrow samples obtained from 10 Ph+ ALL patients. Twenty-seven marrow aspirates were taken from patients in clinical remission (CR). The samples were considered positive for MRD by FC when two conditions were met: 1) detection of an abnormal B-cell differentiation pattern and 2) presence of more than 1x10(-3) cells coexpressing CD22/CD34/CD45 or CD66/CD34/CD10. After FC analysis, RNA was purified using standard methods. FC was positive in 23/27 samples in CR (sensitivity 85%). RT-PCR was successfully performed in 23 samples in CR. RT-PCR was positive in 18/23 samples (sensitivity 78%). There were 5 samples with discordant results. FC was positive in 3 samples with a negative RT-PCR and FC was negative in 2 samples with a positive RT. All the 10 patients relapsed and only 1 is currently alive after an allogeneic stem cell transplantation (alloSCT). The median (range) time from MRD detection to relapse in patients treated with chemotherapy was 42 (39-71) days. These data suggest that RT-PCR may be negative despite the presence of neoplastic cells identified by their immunophenotypic traits. We conclude that immunologic and molecular techniques can be used in tandem for monitoring MRD in Ph+ ALL.
Immunogenic proteins of Brucella abortus to minimize cross reactions in brucellosis diagnosis.

PubMed

Ko, Kyung Yuk; Kim, Jong-Wan; Her, Moon; Kang, Sung-Il; Jung, Suk Chan; Cho, Dong Hee; Kim, Ji-Yeon

2012-05-04

To overcome the limitations of serological diagnosis, including false positive reactions caused by other pathogens, specific antigens for diagnosis of brucellosis other than LPS have been required. The present study was conducted to separate and identify immuno-dominant insoluble proteins of Brucella abortus against the antisera of cattle infected with B. abortus, or/and Yersinia enterocolitica, or the sera of non-infected cattle. After separating insoluble proteins of B. abortus by two dimensional electrophoresis (2-DE), their immuno-reactivity was determined by western blotting. A portion of the immunogenic spots against the positive antisera of B. abortus that have the potential for use as specific antigens were identified by MS/MS analysis. Overall, 18 immunogenic insoluble proteins of B. abortus 1119-3 showed immuno-reactivity against only the positive antisera of B. abortus, but failed to have immunogenicity toward both the positive sera of Y. enterocolitica and the negative sera of B. abortus. Identification of these proteins revealed the following: F0F1 ATP synthase subunit β, solute-binding family 5 protein, 28 kDa OMP, Leu/Ile/Val-binding family protein, Histidinol dehyddrogenase, Hypothetical protein, Twin-arginine translocation pathway signal sequence domain-containing protein, Dihydroorotase, Serine protease family protein, β-hydroxyacyl-(acyl-carrier-protein) dehydratase FabA, Short-chain dehydrogenase-/reductase carbonic anhydrase, Orinithine carbamoyltransferase, Leucyl aminopeptidase, Cold shock DNA-binding domain-containing protein, Cu/Zn superoxide dismutase, and Methionine aminopeptidase. The 18 immunogenic proteins separated in the present study can be considered candidate antigens to minimize cross reaction in the diagnosis of brucellosis and useful sources for Brucella vaccine development. Copyright Â© 2011 Elsevier B.V. All rights reserved.
24 CFR 583.310 - Displacement, relocation, and acquisition.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 24 Housing and Urban Development 3 2010-04-01 2010-04-01 false Displacement, relocation, and....310 Displacement, relocation, and acquisition. (a) Minimizing displacement. Consistent with the other... minimize the displacement of persons (families, individuals, businesses, nonprofit organizations, and farms...
24 CFR 236.1001 - Displacement, relocation, and acquisition.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 24 Housing and Urban Development 2 2012-04-01 2012-04-01 false Displacement, relocation, and... Assistance § 236.1001 Displacement, relocation, and acquisition. (a) Minimizing displacement. Consistent with... reasonable steps to minimize the displacement of persons (households, businesses, nonprofit organizations...
24 CFR 92.353 - Displacement, relocation, and acquisition.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 24 Housing and Urban Development 1 2011-04-01 2011-04-01 false Displacement, relocation, and... Displacement, relocation, and acquisition. (a) Minimizing displacement. Consistent with the other goals and... minimize the displacement of persons (families, individuals, businesses, nonprofit organizations, and farms...
24 CFR 236.1001 - Displacement, relocation, and acquisition.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 24 Housing and Urban Development 2 2011-04-01 2011-04-01 false Displacement, relocation, and... Assistance § 236.1001 Displacement, relocation, and acquisition. (a) Minimizing displacement. Consistent with... reasonable steps to minimize the displacement of persons (households, businesses, nonprofit organizations...
24 CFR 583.310 - Displacement, relocation, and acquisition.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 24 Housing and Urban Development 3 2012-04-01 2012-04-01 false Displacement, relocation, and....310 Displacement, relocation, and acquisition. (a) Minimizing displacement. Consistent with the other... minimize the displacement of persons (families, individuals, businesses, nonprofit organizations, and farms...
24 CFR 92.353 - Displacement, relocation, and acquisition.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 24 Housing and Urban Development 1 2013-04-01 2013-04-01 false Displacement, relocation, and... Displacement, relocation, and acquisition. (a) Minimizing displacement. Consistent with the other goals and... minimize the displacement of persons (families, individuals, businesses, nonprofit organizations, and farms...
24 CFR 92.353 - Displacement, relocation, and acquisition.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 24 Housing and Urban Development 1 2012-04-01 2012-04-01 false Displacement, relocation, and... Displacement, relocation, and acquisition. (a) Minimizing displacement. Consistent with the other goals and... minimize the displacement of persons (families, individuals, businesses, nonprofit organizations, and farms...
24 CFR 578.83 - Displacement, relocation, and acquisition.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 24 Housing and Urban Development 3 2013-04-01 2013-04-01 false Displacement, relocation, and... Displacement, relocation, and acquisition. (a) Minimizing displacement. Consistent with the other goals and... to minimize the displacement of persons (families, individuals, businesses, nonprofit organizations...

24 CFR 92.353 - Displacement, relocation, and acquisition.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 24 Housing and Urban Development 1 2010-04-01 2010-04-01 false Displacement, relocation, and... Displacement, relocation, and acquisition. (a) Minimizing displacement. Consistent with the other goals and... minimize the displacement of persons (families, individuals, businesses, nonprofit organizations, and farms...
24 CFR 236.1001 - Displacement, relocation, and acquisition.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 24 Housing and Urban Development 2 2014-04-01 2014-04-01 false Displacement, relocation, and... Assistance § 236.1001 Displacement, relocation, and acquisition. (a) Minimizing displacement. Consistent with... reasonable steps to minimize the displacement of persons (households, businesses, nonprofit organizations...
24 CFR 583.310 - Displacement, relocation, and acquisition.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 24 Housing and Urban Development 3 2013-04-01 2013-04-01 false Displacement, relocation, and....310 Displacement, relocation, and acquisition. (a) Minimizing displacement. Consistent with the other... minimize the displacement of persons (families, individuals, businesses, nonprofit organizations, and farms...
24 CFR 236.1001 - Displacement, relocation, and acquisition.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 24 Housing and Urban Development 2 2013-04-01 2013-04-01 false Displacement, relocation, and... Assistance § 236.1001 Displacement, relocation, and acquisition. (a) Minimizing displacement. Consistent with... reasonable steps to minimize the displacement of persons (households, businesses, nonprofit organizations...
24 CFR 236.1001 - Displacement, relocation, and acquisition.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 24 Housing and Urban Development 2 2010-04-01 2010-04-01 false Displacement, relocation, and... Assistance § 236.1001 Displacement, relocation, and acquisition. (a) Minimizing displacement. Consistent with... reasonable steps to minimize the displacement of persons (households, businesses, nonprofit organizations...
24 CFR 92.353 - Displacement, relocation, and acquisition.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 24 Housing and Urban Development 1 2014-04-01 2014-04-01 false Displacement, relocation, and... Displacement, relocation, and acquisition. (a) Minimizing displacement. Consistent with the other goals and... minimize the displacement of persons (families, individuals, businesses, nonprofit organizations, and farms...
Root System Water Consumption Pattern Identification on Time Series Data

PubMed Central

Figueroa, Manuel; Pope, Christopher

2017-01-01

In agriculture, soil and meteorological sensors are used along low power networks to capture data, which allows for optimal resource usage and minimizing environmental impact. This study uses time series analysis methods for outliers’ detection and pattern recognition on soil moisture sensor data to identify irrigation and consumption patterns and to improve a soil moisture prediction and irrigation system. This study compares three new algorithms with the current detection technique in the project; the results greatly decrease the number of false positives detected. The best result is obtained by the Series Strings Comparison (SSC) algorithm averaging a precision of 0.872 on the testing sets, vastly improving the current system’s 0.348 precision. PMID:28621739
Root System Water Consumption Pattern Identification on Time Series Data.

PubMed

Figueroa, Manuel; Pope, Christopher

2017-06-16

In agriculture, soil and meteorological sensors are used along low power networks to capture data, which allows for optimal resource usage and minimizing environmental impact. This study uses time series analysis methods for outliers' detection and pattern recognition on soil moisture sensor data to identify irrigation and consumption patterns and to improve a soil moisture prediction and irrigation system. This study compares three new algorithms with the current detection technique in the project; the results greatly decrease the number of false positives detected. The best result is obtained by the Series Strings Comparison (SSC) algorithm averaging a precision of 0.872 on the testing sets, vastly improving the current system's 0.348 precision.
Microaneurysm detection with radon transform-based classification on retina images.

PubMed

Giancardo, L; Meriaudeau, F; Karnowski, T P; Li, Y; Tobin, K W; Chaum, E

2011-01-01

The creation of an automatic diabetic retinopathy screening system using retina cameras is currently receiving considerable interest in the medical imaging community. The detection of microaneurysms is a key element in this effort. In this work, we propose a new microaneurysms segmentation technique based on a novel application of the radon transform, which is able to identify these lesions without any previous knowledge of the retina morphological features and with minimal image preprocessing. The algorithm has been evaluated on the Retinopathy Online Challenge public dataset, and its performance compares with the best current techniques. The performance is particularly good at low false positive ratios, which makes it an ideal candidate for diabetic retinopathy screening systems.
Occupancy models for data with false positive and false negative errors and heterogeneity across sites and surveys

Treesearch

Paige F.B. Ferguson; Michael J. Conroy; Jeffrey Hepinstall-Cymerman; Nigel Yoccoz

2015-01-01

False positive detections, such as species misidentifications, occur in ecological data, although many models do not account for them. Consequently, these models are expected to generate biased inference.The main challenge in an analysis of data with false positives is to distinguish false positive and false negative...
Fuzzy logic-based approach to detecting a passive RFID tag in an outpatient clinic.

PubMed

Min, Daiki; Yih, Yuehwern

2011-06-01

This study is motivated by the observations on the data collected by radio frequency identification (RFID) readers in a pilot study, which was used to investigate the feasibility of implementing an RFID-based monitoring system in an outpatient eye clinic. The raw RFID data collected from RFID readers contain noise and missing reads, which prevent us from determining the tag location. In this paper, fuzzy logic-based algorithms are proposed to interpret the raw RFID data to extract accurate information. The proposed algorithms determine the location of an RFID tag by evaluating its possibility of presence and absence. To evaluate the performance of the proposed algorithms, numerical experiments are conducted using the data observed in the outpatient eye clinic. Experiments results showed that the proposed algorithms outperform existing static smoothing method in terms of minimizing both false positives and false negatives. Furthermore, the proposed algorithms are applied to a set of simulated data to show the robustness of the proposed algorithms at various levels of RFID reader reliability.
Diagnosis of metastatic melanoma by fine-needle biopsy: analysis of 2,204 cases.

PubMed

Murali, Rajmohan; Doubrovsky, Anna; Watson, Geoffrey F; McKenzie, Paul R; Lee, C Soon; McLeod, Duncan J; Uren, Roger F; Stretch, Jonathan R; Saw, Robyn P M; Thompson, John F; Scolyer, Richard A

2007-03-01

Fine-needle biopsy (FNB) has been reported as a rapid, minimally invasive technique for the diagnosis of metastatic melanoma. The diagnostic accuracy of FNB was assessed in a consecutive series of 2,204 FNBs of clinically suspicious lesions from patients with previous primary melanomas treated at the Sydney Melanoma Unit, Sydney, Australia, between January 1992 and December 2002. The sensitivity and specificity of FNB were 96.3% and 98.9%, respectively. There were 5 false-positive cases (0.6%), which were verified as metastatic adenocarcinoma (3 cases) or reactive processes (organizing hematoma and chronic osteomyelitis, 1 each). False-negative diagnoses (6.7% of cases) were associated with a variety of clinicopathologic factors, including difficult-to-access anatomic sites (eg, high axilla or deep inguinal), small lesions, and lesional characteristics such asfibrosis, necrosis, or cystic change. FNB is a highly accurate, rapid, and cost-effective procedure for the diagnosis of metastatic melanoma and should be considered as the initial diagnostic procedure of choice in patients with melanoma with clinically suspected metastases.
How Accurately Can Your Wrist Device Recognize Daily Activities and Detect Falls?

PubMed Central

Gjoreski, Martin; Gjoreski, Hristijan; Luštrek, Mitja; Gams, Matjaž

2016-01-01

Although wearable accelerometers can successfully recognize activities and detect falls, their adoption in real life is low because users do not want to wear additional devices. A possible solution is an accelerometer inside a wrist device/smartwatch. However, wrist placement might perform poorly in terms of accuracy due to frequent random movements of the hand. In this paper we perform a thorough, large-scale evaluation of methods for activity recognition and fall detection on four datasets. On the first two we showed that the left wrist performs better compared to the dominant right one, and also better compared to the elbow and the chest, but worse compared to the ankle, knee and belt. On the third (Opportunity) dataset, our method outperformed the related work, indicating that our feature-preprocessing creates better input data. And finally, on a real-life unlabeled dataset the recognized activities captured the subject’s daily rhythm and activities. Our fall-detection method detected all of the fast falls and minimized the false positives, achieving 85% accuracy on the first dataset. Because the other datasets did not contain fall events, only false positives were evaluated, resulting in 9 for the second, 1 for the third and 15 for the real-life dataset (57 days data). PMID:27258282
Waterway wide area tactical coverage and homing (WaterWATCH) program overview

NASA Astrophysics Data System (ADS)

Driggers, Gerald; Cleveland, Tammy; Araujo, Lisa; Spohr, Robert; Umansky, Mark

2008-04-01

The Congressional and Army sponsored WaterWATCH TM Program has developed and demonstrated a fully integrated shallow water port and facility monitoring system. It provides fully automated monitoring of domains above and below the surface of the water using primarily off-the-shelf sensors and software. The system is modular, open architecture and IP based, and elements can be mixed and matched to adapt to specific applications. The sensors integrated into the WaterWATCH TM system include cameras, radar, passive and active sonar, and various motion detectors. The sensors were chosen based on extensive requirements analyses and tradeoffs. Descriptions of the system and individual sensors are provided, along with data from modular and system level testing. Camera test results address capabilities and limitations associated with using "smart" image analysis software with stressing environmental issues such as bugs, darkness, rain and snow. Radar issues addressed include achieving range and resolution requirements. The passive sonar capability to provide near 100% true positives with zero false positives is demonstrated. Testing results are also presented to show that inexpensive active sonar can be effective against divers with or without SCUBA gear and that false alarms due to fish can be minimized. A simple operator interface has also been demonstrated.
Combination of Autoantibody Signature with PSA Level Enables a Highly Accurate Blood-Based Differentiation of Prostate Cancer Patients from Patients with Benign Prostatic Hyperplasia.

PubMed

Leidinger, Petra; Keller, Andreas; Milchram, Lisa; Harz, Christian; Hart, Martin; Werth, Angelika; Lenhof, Hans-Peter; Weinhäusel, Andreas; Keck, Bastian; Wullich, Bernd; Ludwig, Nicole; Meese, Eckart

2015-01-01

Although an increased level of the prostate-specific antigen can be an indication for prostate cancer, other reasons often lead to a high rate of false positive results. Therefore, an additional serological screening of autoantibodies in patients' sera could improve the detection of prostate cancer. We performed protein macroarray screening with sera from 49 prostate cancer patients, 70 patients with benign prostatic hyperplasia and 28 healthy controls and compared the autoimmune response in those groups. We were able to distinguish prostate cancer patients from normal controls with an accuracy of 83.2%, patients with benign prostatic hyperplasia from normal controls with an accuracy of 86.0% and prostate cancer patients from patients with benign prostatic hyperplasia with an accuracy of 70.3%. Combining seroreactivity pattern with a PSA level of higher than 4.0 ng/ml this classification could be improved to an accuracy of 84.1%. For selected proteins we were able to confirm the differential expression by using luminex on 84 samples. We provide a minimally invasive serological method to reduce false positive results in detection of prostate cancer and according to PSA screening to distinguish men with prostate cancer from men with benign prostatic hyperplasia.
A Realistic Seizure Prediction Study Based on Multiclass SVM.

PubMed

Direito, Bruno; Teixeira, César A; Sales, Francisco; Castelo-Branco, Miguel; Dourado, António

2017-05-01

A patient-specific algorithm, for epileptic seizure prediction, based on multiclass support-vector machines (SVM) and using multi-channel high-dimensional feature sets, is presented. The feature sets, combined with multiclass classification and post-processing schemes aim at the generation of alarms and reduced influence of false positives. This study considers 216 patients from the European Epilepsy Database, and includes 185 patients with scalp EEG recordings and 31 with intracranial data. The strategy was tested over a total of 16,729.80[Formula: see text]h of inter-ictal data, including 1206 seizures. We found an overall sensitivity of 38.47% and a false positive rate per hour of 0.20. The performance of the method achieved statistical significance in 24 patients (11% of the patients). Despite the encouraging results previously reported in specific datasets, the prospective demonstration on long-term EEG recording has been limited. Our study presents a prospective analysis of a large heterogeneous, multicentric dataset. The statistical framework based on conservative assumptions, reflects a realistic approach compared to constrained datasets, and/or in-sample evaluations. The improvement of these results, with the definition of an appropriate set of features able to improve the distinction between the pre-ictal and nonpre-ictal states, hence minimizing the effect of confounding variables, remains a key aspect.
13 CFR 115.34 - Minimization of Surety's Loss.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 13 Business Credit and Assistance 1 2010-01-01 2010-01-01 false Minimization of Surety's Loss. 115.34 Section 115.34 Business Credit and Assistance SMALL BUSINESS ADMINISTRATION SURETY BOND GUARANTEE... strategy in maximizing recovery. See also § 115.17(b). ...
10 CFR 20.1406 - Minimization of contamination.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 1 2013-01-01 2013-01-01 false Minimization of contamination. 20.1406 Section 20.1406 Energy NUCLEAR REGULATORY COMMISSION STANDARDS FOR PROTECTION AGAINST RADIATION Radiological Criteria for... subsurface, in accordance with the existing radiation protection requirements in subpart B and radiological...
10 CFR 20.1406 - Minimization of contamination.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 1 2014-01-01 2014-01-01 false Minimization of contamination. 20.1406 Section 20.1406 Energy NUCLEAR REGULATORY COMMISSION STANDARDS FOR PROTECTION AGAINST RADIATION Radiological Criteria for... subsurface, in accordance with the existing radiation protection requirements in subpart B and radiological...
24 CFR 582.335 - Displacement, relocation, and real property acquisition.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 24 Housing and Urban Development 3 2012-04-01 2012-04-01 false Displacement, relocation, and real....335 Displacement, relocation, and real property acquisition. (a) Minimizing displacement. Consistent... reasonable steps to minimize the displacement of persons (families, individuals, businesses, nonprofit...

24 CFR 582.335 - Displacement, relocation, and real property acquisition.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 24 Housing and Urban Development 3 2013-04-01 2013-04-01 false Displacement, relocation, and real....335 Displacement, relocation, and real property acquisition. (a) Minimizing displacement. Consistent... reasonable steps to minimize the displacement of persons (families, individuals, businesses, nonprofit...
24 CFR 582.335 - Displacement, relocation, and real property acquisition.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 24 Housing and Urban Development 3 2010-04-01 2010-04-01 false Displacement, relocation, and real....335 Displacement, relocation, and real property acquisition. (a) Minimizing displacement. Consistent... reasonable steps to minimize the displacement of persons (families, individuals, businesses, nonprofit...
Proportion hyperglycosylated hCG: a new test for discriminating gestational trophoblastic diseases.

PubMed

Cole, Laurence A

2014-11-01

Hyperglycosylated human chorionic gonadotropin (hCG) is a variant of hCG with large oligosaccharide side chains. Although hCG is produced by syncytiotrophoblast cells, hyperglycosylated hCG marks cytotrophoblast cell. Hyperglycosylated hCG signals placental implantation. Total hCG in serum and urine is measured by the Siemens Immulite hCG pregnancy test; the result is in milli-international unit per milliliter. Hyperglycosylated hCG is determined by the B152 microtiter plate assay; the result is in nanogram per milliliter. Hyperglycosylated hCG results can be converted to milli-international unit per milliliter equivalents by multiplying by 11. The test measures proportion hyperglycosylated hCG, hyperglycosylated hCG / total hCG. Proportion hyperglycosylated hCG marks cases intent on developing persistent hydatidiform mole (68% detection at 17% false detection). Proportion hyperglycosylated hCG also marks persistent hydatidiform mole (100% detection at 5.1% false detection). Proportion hyperglycosylated hCG distinguishes choriocarcinoma and gestational trophoblastic neoplasm cases, absolutely discriminating aggressive cases and minimally aggressive cases. Proportion hyperglycosylated hCG identifies quiescent gestational trophoblastic disease cases. It recognizes quiescent cases that become persistent disease (100% detection at 0% false positive). Proportion hyperglycosylated hCG is an invaluable test for discriminating gestational trophoblastic diseases.
Rapid and reliable determination of illegal adulterant in herbal medicines and dietary supplements by LC/MS/MS.

PubMed

Liang, Qionglin; Qu, Jun; Luo, Guoan; Wang, Yiming

2006-02-13

In recent years, dietary supplements and herbal medicines are increasing in popularity all over the world. However, it is problematic that some manufacturers illegally included synthetic drugs in their products. Due to the extremely complex matrices of those products, most existing methods for screening illegal adulterations are time-consuming and liable to false positive. In this paper, a robust LC/MS/MS method for the high-throughput, sensitive and reliable determination of illegal adulterations from herbal medicines and dietary supplements was established. Minimal LC separation was employed and MRM was used to simultaneously monitor the three transitions under their respective optimal collision energy for each compound. Positive results were determined only if well-defined peaks appeared at all of the three transitions and the ratios among the peak areas were within given threshold. In this study, the method had been applied for the screening of nine most commonly adulterated therapeutic substances, such as sildenafil (Viagra) and famotidine, and the lower limits of detection of these compounds ranged from 0.05 to 1.5 ng/ml. Little sample preparation was needed for this method and the analysis time was less than 5 min/sample. The reliability has been demonstrated by the test with blank matrix. Over 200 products that were under suspicion by SDA of China had been assayed and till now no false negative or positive result was found. This method is rapid, simple, reliable and capable of screening multiple adulterants in one run.
False discovery rates in spectral identification.

PubMed

Jeong, Kyowon; Kim, Sangtae; Bandeira, Nuno

2012-01-01

Automated database search engines are one of the fundamental engines of high-throughput proteomics enabling daily identifications of hundreds of thousands of peptides and proteins from tandem mass (MS/MS) spectrometry data. Nevertheless, this automation also makes it humanly impossible to manually validate the vast lists of resulting identifications from such high-throughput searches. This challenge is usually addressed by using a Target-Decoy Approach (TDA) to impose an empirical False Discovery Rate (FDR) at a pre-determined threshold x% with the expectation that at most x% of the returned identifications would be false positives. But despite the fundamental importance of FDR estimates in ensuring the utility of large lists of identifications, there is surprisingly little consensus on exactly how TDA should be applied to minimize the chances of biased FDR estimates. In fact, since less rigorous TDA/FDR estimates tend to result in more identifications (at higher 'true' FDR), there is often little incentive to enforce strict TDA/FDR procedures in studies where the major metric of success is the size of the list of identifications and there are no follow up studies imposing hard cost constraints on the number of reported false positives. Here we address the problem of the accuracy of TDA estimates of empirical FDR. Using MS/MS spectra from samples where we were able to define a factual FDR estimator of 'true' FDR we evaluate several popular variants of the TDA procedure in a variety of database search contexts. We show that the fraction of false identifications can sometimes be over 10× higher than reported and may be unavoidably high for certain types of searches. In addition, we further report that the two-pass search strategy seems the most promising database search strategy. While unavoidably constrained by the particulars of any specific evaluation dataset, our observations support a series of recommendations towards maximizing the number of resulting identifications while controlling database searches with robust and reproducible TDA estimation of empirical FDR.
A prospective clinical trial to compare the performance of dried blood spots prenatal screening for Down's syndrome with conventional non-invasive testing technology.

PubMed

Hu, Huiying; Jiang, Yulin; Zhang, Minghui; Liu, Shanying; Hao, Na; Zhou, Jing; Liu, Juntao; Zhang, Xiaojin; Ma, Liangkun

2017-03-01

To evaluate, side by side, the efficiency of dried blood spots (DBSs) against serum screening for Down's syndrome, and then, to construct a two-tier strategy by topping up the fetal cell-free DNA (cfDNA) secondary screening over the high-risk women marked by the primary blood testing to build a practical screening tactic to identify fetal Down's syndrome. One thousand eight hundred and thirty-seven low-risk Chinese women, with singleton pregnancy, were enrolled for the study. Alpha-fetoprotein and free beta human chorionic gonadotropin were measured for the serum as well as for the parallel DBS samples. Partial high-risk pregnant women identified by primary blood testing (n = 38) were also subject to the secondary cfDNA screening. Diagnostic amniocentesis was utilized to confirm the screening results. The true positive rate for Down's syndrome detection was 100% for both blood screening methods; however, the false-positive rate was 3.0% for DBS and 4.0% for serum screening, respectively. DBS correlated well with serum screening on Down's syndrome detection. Three out of 38 primary high-risk women displayed chromosomal abnormalities by cfDNA analysis, which were confirmed by amniocentesis. Either the true detection rate or the false-positive rate for Down's syndrome between DBS and the serum test is comparable. In addition, blood primary screening aligned with secondary cfDNA analysis, a "before and after" two-tier screening strategy, can massively decrease the false-positive rate, which, then, dramatically reduces the demand for invasive diagnostic operation. Impact statement Children born with Down's syndrome display a wide range of mental and physical disability. Currently, there is no effective treatment to ease the burden and anxiety of the Down's syndrome family and the surrounding society. This study is to evaluate the efficiency of dried blood spots against serum screening for Down's syndrome and to construct a two-tier strategy by topping up the fetal cell-free DNA (cfDNA) secondary screening over the high-risk women marked by the primary blood testing to build a practical screening tactic to identify fetal Down's syndrome. Results demonstrate that fetal cfDNA can significantly reduce false-positive rate close to none while distinguishing all true positives. Thus, we recommend that fetal cfDNA analysis to be utilized as a secondary screening tool atop of the primary blood protein screening to further minimize the capacity of undesirable invasive diagnostic operations.
Background parenchymal enhancement in preoperative breast MRI.

PubMed

Kohara, Satoko; Ishigaki, Satoko; Satake, Hiroko; Kawamura, Akiko; Kawai, Hisashi; Kikumori, Toyone; Naganawa, Shinji

2015-08-01

We aimed to assess the influence of background parenchymal enhancement (BPE) on surgical planning performed using preoperative MRI for breast cancer evaluation. Between January 2009 and December 2010, 91 newly diagnosed breast cancer patients (mean age, 55.5 years; range, 30-88 years) who underwent preoperative bilateral breast MRI followed by planned breast conservation therapy were retrospectively enrolled. MRI was performed to assess the tumor extent in addition to mammography and breast ultrasonography. BPE in the contralateral normal breast MRI at the early dynamic phase was visually classified as follows: minimal (n=49), mild (n=27), moderate (n=7), and marked (n=8). The correlations between the BPE grade and age, menopausal status, index tumor size, changes in surgical management based on MRI results, positive predictive value (PPV) of MRI, and surgical margins were assessed. Patients in the strong BPE groups were significantly younger (p=0.002) and generally premenopausal (p<0.001). Surgical treatment was not changed in 67 cases (73.6%), while extended excision and mastectomy were performed in 12 cases (13.2%), each based on additional lesions on MRI. Six of 79 (7.6%) patients who underwent breast conservation therapy had tumor-positive resection margins. In cases where surgical management was changed, the PPV for MRI-detected foci was high in the minimal (91.7%) and mild groups (66.7%), and 0% in the moderate and marked groups (p=0.002). Strong BPE causes false-positive MRI findings and may lead to overly extensive surgery, whereas MRI may be beneficial in select patients with weak BPE.
10 CFR 20.1406 - Minimization of contamination.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 1 2012-01-01 2012-01-01 false Minimization of contamination. 20.1406 Section 20.1406 Energy NUCLEAR REGULATORY COMMISSION STANDARDS FOR PROTECTION AGAINST RADIATION Radiological Criteria for..., including the subsurface, in accordance with the existing radiation protection requirements in Subpart B and...
24 CFR 576.408 - Displacement, relocation, and acquisition.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 24 Housing and Urban Development 3 2012-04-01 2012-04-01 false Displacement, relocation, and... § 576.408 Displacement, relocation, and acquisition. (a) Minimizing displacement. Consistent with the... assure that they have taken all reasonable steps to minimize the displacement of persons (families...
24 CFR 576.408 - Displacement, relocation, and acquisition.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 24 Housing and Urban Development 3 2013-04-01 2013-04-01 false Displacement, relocation, and... § 576.408 Displacement, relocation, and acquisition. (a) Minimizing displacement. Consistent with the... assure that they have taken all reasonable steps to minimize the displacement of persons (families...
Identifying Epigenetic Biomarkers using Maximal Relevance and Minimal Redundancy Based Feature Selection for Multi-Omics Data.

PubMed

Mallik, Saurav; Bhadra, Tapas; Maulik, Ujjwal

2017-01-01

Epigenetic Biomarker discovery is an important task in bioinformatics. In this article, we develop a new framework of identifying statistically significant epigenetic biomarkers using maximal-relevance and minimal-redundancy criterion based feature (gene) selection for multi-omics dataset. Firstly, we determine the genes that have both expression as well as methylation values, and follow normal distribution. Similarly, we identify the genes which consist of both expression and methylation values, but do not follow normal distribution. For each case, we utilize a gene-selection method that provides maximal-relevant, but variable-weighted minimum-redundant genes as top ranked genes. For statistical validation, we apply t-test on both the expression and methylation data consisting of only the normally distributed top ranked genes to determine how many of them are both differentially expressed andmethylated. Similarly, we utilize Limma package for performing non-parametric Empirical Bayes test on both expression and methylation data comprising only the non-normally distributed top ranked genes to identify how many of them are both differentially expressed and methylated. We finally report the top-ranking significant gene-markerswith biological validation. Moreover, our framework improves positive predictive rate and reduces false positive rate in marker identification. In addition, we provide a comparative analysis of our gene-selection method as well as othermethods based on classificationperformances obtained using several well-known classifiers.
Lyapunov Exponents of Minimizing Measures for Globally Positive Diffeomorphisms in All Dimensions

NASA Astrophysics Data System (ADS)

Arnaud, M.-C.

2016-05-01

The globally positive diffeomorphisms of the 2 n-dimensional annulus are important because they represent what happens close to a completely elliptic periodic point of a symplectic diffeomorphism where the torsion is positive definite. For these globally positive diffeomorphisms, an Aubry-Mather theory was developed by Garibaldi and Thieullen that provides the existence of some minimizing measures. Using the two Green bundles {G_-} and {G_+} that can be defined along the support of these minimizing measures, we will prove that there is a deep link between: the angle between {G_-} and {G_+} along the support of the considered measure {μ};
Improving computer-aided detection assistance in breast cancer screening by removal of obviously false-positive findings.

PubMed

Mordang, Jan-Jurre; Gubern-Mérida, Albert; Bria, Alessandro; Tortorella, Francesco; den Heeten, Gerard; Karssemeijer, Nico

2017-04-01

Computer-aided detection (CADe) systems for mammography screening still mark many false positives. This can cause radiologists to lose confidence in CADe, especially when many false positives are obviously not suspicious to them. In this study, we focus on obvious false positives generated by microcalcification detection algorithms. We aim at reducing the number of obvious false-positive findings by adding an additional step in the detection method. In this step, a multiclass machine learning method is implemented in which dedicated classifiers learn to recognize the patterns of obvious false-positive subtypes that occur most frequently. The method is compared to a conventional two-class approach, where all false-positive subtypes are grouped together in one class, and to the baseline CADe system without the new false-positive removal step. The methods are evaluated on an independent dataset containing 1,542 screening examinations of which 80 examinations contain malignant microcalcifications. Analysis showed that the multiclass approach yielded a significantly higher sensitivity compared to the other two methods (P < 0.0002). At one obvious false positive per 100 images, the baseline CADe system detected 61% of the malignant examinations, while the systems with the two-class and multiclass false-positive reduction step detected 73% and 83%, respectively. Our study showed that by adding the proposed method to a CADe system, the number of obvious false positives can decrease significantly (P < 0.0002). © 2017 American Association of Physicists in Medicine.
Intersection-Controller Software Module

NASA Technical Reports Server (NTRS)

Bachelder, Aaron; Foster, Conrad

2005-01-01

An important part of the emergency-vehicle traffic-light-preemption system summarized in the preceding article is a software module executed by a microcontroller in each intersection controller. This module monitors the broadcasts from all nearby participating emergency vehicles and intersections. It gathers the broadcast data pertaining to the positions and velocities of the vehicles and the timing of traffic and pedestrian lights and processes the data into predictions of the future positions of the vehicles. Analyzing the predictions by a combination of proximity tests, map-matching techniques, and statistical calculations designed to minimize the adverse effects of uncertainties in vehicle positions and headings, the module decides whether to preempt and issues the appropriate commands to the traffic lights, pedestrian lights, and electronic warning signs at the intersection. The module also broadcasts its state to all nearby vehicles and intersections. The module is designed to mitigate the effects of missing data and of unpredictable delays in the system. It has been intensively tested and refined so that it fails to warn in very few cases and issues very few false warnings.
The utility and interpretation of tuberculin skin tests in the Middle East.

PubMed

Al-Jahdali, Hamdan; Memish, Ziad A; Menzies, Dick

2005-04-01

Tuberculin skin test (TST) interpretation can be confounded by Bacillus Calmette-Guerin (BCG) vaccination and infection with nontuberculosis mycobacteria (NTM). However, a wealth of epidemiologic information has allowed the formulation of recommendations for reasonably informed interpretation of the TST in most clinical situations. In the Middle East, the TST remains a useful test. BCG vaccination is given at birth, which should have minimal effect on TST reactions in adolescents or adults. In countries of the Middle East with moderate to high incidence of active smear-positive pulmonary TB (>20 per 100,000 per year), a positive TST will almost always indicate true TB infection. However, in Middle East countries with very low incidence of active TB (<10 per 100,000 per year), a positive TST will more likely be false positive because BCG vaccination is still routinely given; until BCG vaccination is abandoned, the TST will be less useful in these countries. These findings are applicable to countries in other regions of the world, and the utility TST will also be increased where the likelihood of TB infection is higher and lowered where TB infection is unlikely, yet BCG vaccination is still given.
14 CFR 27.610 - Lightning and static electricity protection.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Lightning and static electricity protection....610 Lightning and static electricity protection. (a) The rotorcraft must be protected against... static electricity must— (1) Minimize the accumulation of electrostatic charge; (2) Minimize the risk of...
14 CFR 27.610 - Lightning and static electricity protection.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Lightning and static electricity protection....610 Lightning and static electricity protection. (a) The rotorcraft must be protected against... static electricity must— (1) Minimize the accumulation of electrostatic charge; (2) Minimize the risk of...
14 CFR 27.610 - Lightning and static electricity protection.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Lightning and static electricity protection....610 Lightning and static electricity protection. (a) The rotorcraft must be protected against... static electricity must— (1) Minimize the accumulation of electrostatic charge; (2) Minimize the risk of...
14 CFR 27.610 - Lightning and static electricity protection.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Lightning and static electricity protection....610 Lightning and static electricity protection. (a) The rotorcraft must be protected against... static electricity must— (1) Minimize the accumulation of electrostatic charge; (2) Minimize the risk of...
14 CFR 27.610 - Lightning and static electricity protection.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Lightning and static electricity protection....610 Lightning and static electricity protection. (a) The rotorcraft must be protected against... static electricity must— (1) Minimize the accumulation of electrostatic charge; (2) Minimize the risk of...

Minimal sufficient positive-operator valued measure on a separable Hilbert space

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuramochi, Yui, E-mail: kuramochi.yui.22c@st.kyoto-u.ac.jp

We introduce a concept of a minimal sufficient positive-operator valued measure (POVM), which is the least redundant POVM among the POVMs that have the equivalent information about the measured quantum system. Assuming the system Hilbert space to be separable, we show that for a given POVM, a sufficient statistic called a Lehmann-Scheffé-Bahadur statistic induces a minimal sufficient POVM. We also show that every POVM has an equivalent minimal sufficient POVM and that such a minimal sufficient POVM is unique up to relabeling neglecting null sets. We apply these results to discrete POVMs and information conservation conditions proposed by the author.
Optimizing the TESS Planet Finding Pipeline

NASA Astrophysics Data System (ADS)

Chitamitara, Aerbwong; Smith, Jeffrey C.; Tenenbaum, Peter; TESS Science Processing Operations Center

2017-10-01

The Transiting Exoplanet Survey Satellite (TESS) is a new NASA planet finding all-sky survey that will observe stars within 200 light years and 10-100 times brighter than that of the highly successful Kepler mission. TESS is expected to detect ~1000 planets smaller than Neptune and dozens of Earth size planets. As in the Kepler mission, the Science Processing Operations Center (SPOC) processing pipeline at NASA Ames Research center is tasked with calibrating the raw pixel data, generating systematic error corrected light curves and then detecting and validating transit signals. The Transiting Planet Search (TPS) component of the pipeline must be modified and tuned for the new data characteristics in TESS. For example, due to each sector being viewed for as little as 28 days, the pipeline will be identifying transiting planets based on a minimum of two transit signals rather than three, as in the Kepler mission. This may result in a significantly higher false positive rate. The study presented here is to measure the detection efficiency of the TESS pipeline using simulated data. Transiting planets identified by TPS are compared to transiting planets from the simulated transit model using the measured epochs, periods, transit durations and the expected detection statistic of injected transit signals (expected MES). From the comparisons, the recovery and false positive rates of TPS is measured. Measurements of recovery in TPS are then used to adjust TPS configuration parameters to maximize the planet recovery rate and minimize false detections. The improvements in recovery rate between initial TPS conditions and after various adjustments will be presented and discussed.
Changing perspectives in screening for congenital hypothyroidism and congenital adrenal hyperplasia.

PubMed

Mitchell, Marvin L; Hsu, Ho-Wen; Sahai, Inderneel

2014-02-01

The purpose of this review is to summarize recent information that has had a significant impact on the laboratory diagnosis and clinical management of newborns with congenital hypothyroidism and congenital adrenal hyperplasia (CAH). An approximate doubling of the incidence rate of congenital hypothyroidism in many parts of the world has been attributed to increased detection of infants with mild disease, delayed thyroid stimulating hormone elevations and demographic changes. A substantial number of children with modest thyroid stimulating hormone elevations on screening have permanent disease. Circulating levels of thyroxine may vary among hypothyroid children who are given identical dosages of medication. Treated infants should be monitored every 1-2 months during the first year of life. Although, generic and brand name thyroxine preparations may not be bioequivalent, children can be well controlled on generic formulations.Enzyme linked immunoassay assay for 17-hydroxyprogesterone is associated with a high rate of false positive specimens. In attempts to minimize this problem, some programs have resorted to two-tier screening of the initial specimen with steroid profiling as the second tier. Several programs are routinely testing second specimens in an effort to reduce the incidence of missed CAH cases. This review explains the uptick in incidence rate of congenital hypothyroidism and underscores issues in management that can affect developmental outcome. One specimen two-tier testing for CAH resulted in an increased false negative rate without significantly reducing the false positive rate. The benefit of collecting second specimens for CAH screening is problematic. Optimal treatment of CAH continues to pose a challenge.
Statistical approaches to account for false-positive errors in environmental DNA samples.

PubMed

Lahoz-Monfort, José J; Guillera-Arroita, Gurutzeta; Tingley, Reid

2016-05-01

Environmental DNA (eDNA) sampling is prone to both false-positive and false-negative errors. We review statistical methods to account for such errors in the analysis of eDNA data and use simulations to compare the performance of different modelling approaches. Our simulations illustrate that even low false-positive rates can produce biased estimates of occupancy and detectability. We further show that removing or classifying single PCR detections in an ad hoc manner under the suspicion that such records represent false positives, as sometimes advocated in the eDNA literature, also results in biased estimation of occupancy, detectability and false-positive rates. We advocate alternative approaches to account for false-positive errors that rely on prior information, or the collection of ancillary detection data at a subset of sites using a sampling method that is not prone to false-positive errors. We illustrate the advantages of these approaches over ad hoc classifications of detections and provide practical advice and code for fitting these models in maximum likelihood and Bayesian frameworks. Given the severe bias induced by false-negative and false-positive errors, the methods presented here should be more routinely adopted in eDNA studies. © 2015 John Wiley & Sons Ltd.
Easy fix for clinical laboratories for the false-positive defect with the Abbott AxSym total beta-hCG test.

PubMed

Cole, Laurence A; Khanlian, Sarah A

2004-05-01

False-positive hCG results can lead to erroneous diagnoses and needless chemotherapy and surgery. In the last 2 years, eight publications described cases involving false-positive hCG tests; all eight involved the AxSym test. We investigated the source of this abundance of cases and a simple fix that may be used by clinical laboratories. False-positive hCG was primarily identified by absence of hCG in urine and varying or negative hCG results in alternative tests. Seventeen false-positive serum samples in the AxSym test were evaluated undiluted and at twofold dilution with diluent containing excess goat serum or immunoglobulin. We identified 58 patients with false-positive hCG, 47 of 58 due to the Abbott AxSym total hCGbeta test (81%). Sixteen of 17 of these "false-positive" results (mean 100 mIU/ml) became undetectable when tested again after twofold dilution. A simple twofold dilution with this diluent containing excess goat serum or immunoglobulin completely protected 16 of 17 samples from patients having false-positive results. It is recommended that laboratories using this test use twofold dilution as a minimum to prevent false-positive results.
CT Colonography with Computer-aided Detection: Recognizing the Causes of False-Positive Reader Results

PubMed Central

Dachman, Abraham H.; Wroblewski, Kristen; Vannier, Michael W.; Horne, John M.

2014-01-01

Computed tomography (CT) colonography is a screening modality used to detect colonic polyps before they progress to colorectal cancer. Computer-aided detection (CAD) is designed to decrease errors of detection by finding and displaying polyp candidates for evaluation by the reader. CT colonography CAD false-positive results are common and have numerous causes. The relative frequency of CAD false-positive results and their effect on reader performance on the basis of a 19-reader, 100-case trial shows that the vast majority of CAD false-positive results were dismissed by readers. Many CAD false-positive results are easily disregarded, including those that result from coarse mucosa, reconstruction, peristalsis, motion, streak artifacts, diverticulum, rectal tubes, and lipomas. CAD false-positive results caused by haustral folds, extracolonic candidates, diminutive lesions (<6 mm), anal papillae, internal hemorrhoids, varices, extrinsic compression, and flexural pseudotumors are almost always recognized and disregarded. The ileocecal valve and tagged stool are common sources of CAD false-positive results associated with reader false-positive results. Nondismissable CAD soft-tissue polyp candidates larger than 6 mm are another common cause of reader false-positive results that may lead to further evaluation with follow-up CT colonography or optical colonoscopy. Strategies for correctly evaluating CAD polyp candidates are important to avoid pitfalls from common sources of CAD false-positive results. ©RSNA, 2014 PMID:25384290
21 CFR 50.51 - Clinical investigations not involving greater than minimal risk.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Clinical investigations not involving greater than... HUMAN SERVICES GENERAL PROTECTION OF HUMAN SUBJECTS Additional Safeguards for Children in Clinical Investigations § 50.51 Clinical investigations not involving greater than minimal risk. Any clinical...
40 CFR 230.75 - Actions affecting plant and animal populations.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 25 2011-07-01 2011-07-01 false Actions affecting plant and animal... Actions To Minimize Adverse Effects § 230.75 Actions affecting plant and animal populations. Minimization of adverse effects on populations of plants and animals can be achieved by: (a) Avoiding changes in...
40 CFR 230.75 - Actions affecting plant and animal populations.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 26 2013-07-01 2013-07-01 false Actions affecting plant and animal... Actions To Minimize Adverse Effects § 230.75 Actions affecting plant and animal populations. Minimization of adverse effects on populations of plants and animals can be achieved by: (a) Avoiding changes in...
40 CFR 230.75 - Actions affecting plant and animal populations.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 25 2014-07-01 2014-07-01 false Actions affecting plant and animal... Actions To Minimize Adverse Effects § 230.75 Actions affecting plant and animal populations. Minimization of adverse effects on populations of plants and animals can be achieved by: (a) Avoiding changes in...
14 CFR 29.610 - Lightning and static electricity protection.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Lightning and static electricity protection... § 29.610 Lightning and static electricity protection. (a) The rotorcraft structure must be protected... electricity must— (1) Minimize the accumulation of electrostatic charge; (2) Minimize the risk of electric...
14 CFR 29.610 - Lightning and static electricity protection.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Lightning and static electricity protection... § 29.610 Lightning and static electricity protection. (a) The rotorcraft structure must be protected... electricity must— (1) Minimize the accumulation of electrostatic charge; (2) Minimize the risk of electric...
14 CFR 29.610 - Lightning and static electricity protection.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Lightning and static electricity protection... § 29.610 Lightning and static electricity protection. (a) The rotorcraft structure must be protected... electricity must— (1) Minimize the accumulation of electrostatic charge; (2) Minimize the risk of electric...
14 CFR 29.610 - Lightning and static electricity protection.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Lightning and static electricity protection... § 29.610 Lightning and static electricity protection. (a) The rotorcraft structure must be protected... electricity must— (1) Minimize the accumulation of electrostatic charge; (2) Minimize the risk of electric...
14 CFR 29.610 - Lightning and static electricity protection.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Lightning and static electricity protection... § 29.610 Lightning and static electricity protection. (a) The rotorcraft structure must be protected... electricity must— (1) Minimize the accumulation of electrostatic charge; (2) Minimize the risk of electric...
36 CFR 228.8 - Requirements for environmental protection.

Code of Federal Regulations, 2012 CFR

2012-07-01

... shall be conducted so as, where feasible, to minimize adverse environmental impacts on National Forest..., shall either be removed from National Forest lands or disposed of or treated so as to minimize, so far... 36 Parks, Forests, and Public Property 2 2012-07-01 2012-07-01 false Requirements for...
36 CFR 228.8 - Requirements for environmental protection.

Code of Federal Regulations, 2014 CFR

2014-07-01

... shall be conducted so as, where feasible, to minimize adverse environmental impacts on National Forest..., shall either be removed from National Forest lands or disposed of or treated so as to minimize, so far... 36 Parks, Forests, and Public Property 2 2014-07-01 2014-07-01 false Requirements for...
36 CFR 228.8 - Requirements for environmental protection.

Code of Federal Regulations, 2013 CFR

2013-07-01

... shall be conducted so as, where feasible, to minimize adverse environmental impacts on National Forest..., shall either be removed from National Forest lands or disposed of or treated so as to minimize, so far... 36 Parks, Forests, and Public Property 2 2013-07-01 2013-07-01 false Requirements for...
7 CFR 3430.36 - Procedures to minimize or eliminate duplication of effort.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 7 Agriculture 15 2011-01-01 2011-01-01 false Procedures to minimize or eliminate duplication of effort. 3430.36 Section 3430.36 Agriculture Regulations of the Department of Agriculture (Continued) NATIONAL INSTITUTE OF FOOD AND AGRICULTURE COMPETITIVE AND NONCOMPETITIVE NON-FORMULA FEDERAL ASSISTANCE...
40 CFR 63.543 - What are my standards for process vents?

Code of Federal Regulations, 2014 CFR

2014-07-01

... develop and follow standard operating procedures designed to minimize emissions of total hydrocarbon for... manufacturer's recommended procedures, if available, and the standard operating procedures designed to minimize... 40 Protection of Environment 10 2014-07-01 2014-07-01 false What are my standards for process...

40 CFR 230.76 - Actions affecting human use.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 26 2013-07-01 2013-07-01 false Actions affecting human use. 230.76... Minimize Adverse Effects § 230.76 Actions affecting human use. Minimization of adverse effects on human use... aquatic areas; (c) Timing the discharge to avoid the seasons or periods when human recreational activity...
40 CFR 230.76 - Actions affecting human use.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 25 2014-07-01 2014-07-01 false Actions affecting human use. 230.76... Minimize Adverse Effects § 230.76 Actions affecting human use. Minimization of adverse effects on human use... aquatic areas; (c) Timing the discharge to avoid the seasons or periods when human recreational activity...
40 CFR 230.76 - Actions affecting human use.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 24 2010-07-01 2010-07-01 false Actions affecting human use. 230.76... Minimize Adverse Effects § 230.76 Actions affecting human use. Minimization of adverse effects on human use... aquatic areas; (c) Timing the discharge to avoid the seasons or periods when human recreational activity...
40 CFR 230.76 - Actions affecting human use.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 25 2011-07-01 2011-07-01 false Actions affecting human use. 230.76... Minimize Adverse Effects § 230.76 Actions affecting human use. Minimization of adverse effects on human use... aquatic areas; (c) Timing the discharge to avoid the seasons or periods when human recreational activity...
Improving Echo-Guided Procedures Using an Ultrasound-CT Image Fusion System.

PubMed

Diana, Michele; Halvax, Peter; Mertz, Damien; Legner, Andras; Brulé, Jean-Marcel; Robinet, Eric; Mutter, Didier; Pessaux, Patrick; Marescaux, Jacques

2015-06-01

Image fusion between ultrasound (US) and computed tomography (CT) scan or magnetic resonance can increase operator accuracy in targeting liver lesions, particularly when those are undetectable with US alone. We have developed a modular gel to simulate hepatic solid lesions for educational purposes in imaging and minimally invasive ablation techniques. We aimed to assess the impact of image fusion in targeting artificial hepatic lesions during the hands-on part of 2 courses (basic and advanced) in hepatobiliary surgery. Under US guidance, 10 fake tumors of various sizes were created in the livers of 2 pigs, by percutaneous injection of a biocompatible gel engineered to be hyperdense on CT scanning and barely detectable on US. A CT scan was obtained and a CT-US image fusion was performed using the ACUSON S3000 US system (Siemens Healthcare, Germany). A total of 12 blinded course attendants, were asked in turn to perform a 10-minute liver scan with US alone followed by a 10-minute scan using image fusion. Using US alone, the expert managed to identify all lesions successfully. The true positive rate for course attendants with US alone was 14/36 and 2/24 in the advanced and basic courses, respectively. The total number of false positives identified was 26. With image fusion, the rate of true positives significantly increased to 31/36 (P < .001) in the advanced group and 16/24 in the basic group (P < .001). The total number of false positives, considering all participants, decreased to 4 (P < .001). Image fusion significantly increases accuracy in targeting hepatic lesions and might improve echo-guided procedures. © The Author(s) 2015.
A new pooling strategy for high-throughput screening: the Shifted Transversal Design

PubMed Central

Thierry-Mieg, Nicolas

2006-01-01

Background In binary high-throughput screening projects where the goal is the identification of low-frequency events, beyond the obvious issue of efficiency, false positives and false negatives are a major concern. Pooling constitutes a natural solution: it reduces the number of tests, while providing critical duplication of the individual experiments, thereby correcting for experimental noise. The main difficulty consists in designing the pools in a manner that is both efficient and robust: few pools should be necessary to correct the errors and identify the positives, yet the experiment should not be too vulnerable to biological shakiness. For example, some information should still be obtained even if there are slightly more positives or errors than expected. This is known as the group testing problem, or pooling problem. Results In this paper, we present a new non-adaptive combinatorial pooling design: the "shifted transversal design" (STD). It relies on arithmetics, and rests on two intuitive ideas: minimizing the co-occurrence of objects, and constructing pools of constant-sized intersections. We prove that it allows unambiguous decoding of noisy experimental observations. This design is highly flexible, and can be tailored to function robustly in a wide range of experimental settings (i.e., numbers of objects, fractions of positives, and expected error-rates). Furthermore, we show that our design compares favorably, in terms of efficiency, to the previously described non-adaptive combinatorial pooling designs. Conclusion This method is currently being validated by field-testing in the context of yeast-two-hybrid interactome mapping, in collaboration with Marc Vidal's lab at the Dana Farber Cancer Institute. Many similar projects could benefit from using the Shifted Transversal Design. PMID:16423300
A Closer Look at Self-Reported Suicide Attempts: False Positives and False Negatives

ERIC Educational Resources Information Center

Ploderl, Martin; Kralovec, Karl; Yazdi, Kurosch; Fartacek, Reinhold

2011-01-01

The validity of self-reported suicide attempt information is undermined by false positives (e.g., incidences without intent to die), or by unreported suicide attempts, referred to as false negatives. In a sample of 1,385 Austrian adults, we explored the occurrence of false positives and false negatives with detailed, probing questions. Removing…
Validation Test Results for Orthogonal Probe Eddy Current Thruster Inspection System

NASA Technical Reports Server (NTRS)

Wincheski, Russell A.

2007-01-01

Recent nondestructive evaluation efforts within NASA have focused on an inspection system for the detection of intergranular cracking originating in the relief radius of Primary Reaction Control System (PCRS) Thrusters. Of particular concern is deep cracking in this area which could lead to combustion leakage in the event of through wall cracking from the relief radius into an acoustic cavity of the combustion chamber. In order to reliably detect such defects while ensuring minimal false positives during inspection, the Orthogonal Probe Eddy Current (OPEC) system has been developed and an extensive validation study performed. This report describes the validation procedure, sample set, and inspection results as well as comparing validation flaws with the response from naturally occuring damage.
Enhancing the detection of barcoded reads in high throughput DNA sequencing data by controlling the false discovery rate.

PubMed

Buschmann, Tilo; Zhang, Rong; Brash, Douglas E; Bystrykh, Leonid V

2014-08-07

DNA barcodes are short unique sequences used to label DNA or RNA-derived samples in multiplexed deep sequencing experiments. During the demultiplexing step, barcodes must be detected and their position identified. In some cases (e.g., with PacBio SMRT), the position of the barcode and DNA context is not well defined. Many reads start inside the genomic insert so that adjacent primers might be missed. The matter is further complicated by coincidental similarities between barcode sequences and reference DNA. Therefore, a robust strategy is required in order to detect barcoded reads and avoid a large number of false positives or negatives.For mass inference problems such as this one, false discovery rate (FDR) methods are powerful and balanced solutions. Since existing FDR methods cannot be applied to this particular problem, we present an adapted FDR method that is suitable for the detection of barcoded reads as well as suggest possible improvements. In our analysis, barcode sequences showed high rates of coincidental similarities with the Mus musculus reference DNA. This problem became more acute when the length of the barcode sequence decreased and the number of barcodes in the set increased. The method presented in this paper controls the tail area-based false discovery rate to distinguish between barcoded and unbarcoded reads. This method helps to establish the highest acceptable minimal distance between reads and barcode sequences. In a proof of concept experiment we correctly detected barcodes in 83% of the reads with a precision of 89%. Sensitivity improved to 99% at 99% precision when the adjacent primer sequence was incorporated in the analysis. The analysis was further improved using a paired end strategy. Following an analysis of the data for sequence variants induced in the Atp1a1 gene of C57BL/6 murine melanocytes by ultraviolet light and conferring resistance to ouabain, we found no evidence of cross-contamination of DNA material between samples. Our method offers a proper quantitative treatment of the problem of detecting barcoded reads in a noisy sequencing environment. It is based on the false discovery rate statistics that allows a proper trade-off between sensitivity and precision to be chosen.
Optimization of rotamers prior to template minimization improves stability predictions made by computational protein design.

PubMed

Davey, James A; Chica, Roberto A

2015-04-01

Computational protein design (CPD) predictions are highly dependent on the structure of the input template used. However, it is unclear how small differences in template geometry translate to large differences in stability prediction accuracy. Herein, we explored how structural changes to the input template affect the outcome of stability predictions by CPD. To do this, we prepared alternate templates by Rotamer Optimization followed by energy Minimization (ROM) and used them to recapitulate the stability of 84 protein G domain β1 mutant sequences. In the ROM process, side-chain rotamers for wild-type (WT) or mutant sequences are optimized on crystal or nuclear magnetic resonance (NMR) structures prior to template minimization, resulting in alternate structures termed ROM templates. We show that use of ROM templates prepared from sequences known to be stable results predominantly in improved prediction accuracy compared to using the minimized crystal or NMR structures. Conversely, ROM templates prepared from sequences that are less stable than the WT reduce prediction accuracy by increasing the number of false positives. These observed changes in prediction outcomes are attributed to differences in side-chain contacts made by rotamers in ROM templates. Finally, we show that ROM templates prepared from sequences that are unfolded or that adopt a nonnative fold result in the selective enrichment of sequences that are also unfolded or that adopt a nonnative fold, respectively. Our results demonstrate the existence of a rotamer bias caused by the input template that can be harnessed to skew predictions toward sequences displaying desired characteristics. © 2014 The Protein Society.
Lung fissure detection in CT images using global minimal paths

NASA Astrophysics Data System (ADS)

Appia, Vikram; Patil, Uday; Das, Bipul

2010-03-01

Pulmonary fissures separate human lungs into five distinct regions called lobes. Detection of fissure is essential for localization of the lobar distribution of lung diseases, surgical planning and follow-up. Treatment planning also requires calculation of the lobe volume. This volume estimation mandates accurate segmentation of the fissures. Presence of other structures (like vessels) near the fissure, along with its high variational probability in terms of position, shape etc. makes the lobe segmentation a challenging task. Also, false incomplete fissures and occurrence of diseases add to the complications of fissure detection. In this paper, we propose a semi-automated fissure segmentation algorithm using a minimal path approach on CT images. An energy function is defined such that the path integral over the fissure is the global minimum. Based on a few user defined points on a single slice of the CT image, the proposed algorithm minimizes a 2D energy function on the sagital slice computed using (a) intensity (b) distance of the vasculature, (c) curvature in 2D, (d) continuity in 3D. The fissure is the infimum energy path between a representative point on the fissure and nearest lung boundary point in this energy domain. The algorithm has been tested on 10 CT volume datasets acquired from GE scanners at multiple clinical sites. The datasets span through different pathological conditions and varying imaging artifacts.
"False Positive" Claims of Near-Death Experiences and "False Negative" Denials of Near-Death Experiences

ERIC Educational Resources Information Center

Greyson, Bruce

2005-01-01

Some persons who claim to have had near-death experiences (NDEs) fail research criteria for having had NDEs ("false positives"); others who deny having had NDEs do meet research criteria for having had NDEs ("false negatives"). The author evaluated false positive claims and false negative denials in an organization that promotes near-death…
Risk of breast cancer after false-positive results in mammographic screening.

PubMed

Román, Marta; Castells, Xavier; Hofvind, Solveig; von Euler-Chelpin, My

2016-06-01

Women with false-positive results are commonly referred back to routine screening. Questions remain regarding their long-term outcome of breast cancer. We assessed the risk of screen-detected breast cancer in women with false-positive results. We conducted a joint analysis using individual level data from the population-based screening programs in Copenhagen and Funen in Denmark, Norway, and Spain. Overall, 150,383 screened women from Denmark (1991-2008), 612,138 from Norway (1996-2010), and 1,172,572 from Spain (1990-2006) were included. Poisson regression was used to estimate the relative risk (RR) of screen-detected cancer for women with false-positive versus negative results. We analyzed information from 1,935,093 women 50-69 years who underwent 6,094,515 screening exams. During an average 5.8 years of follow-up, 230,609 (11.9%) women received a false-positive result and 27,849 (1.4%) were diagnosed with screen-detected cancer. The adjusted RR of screen-detected cancer after a false-positive result was 2.01 (95% CI: 1.93-2.09). Women who tested false-positive at first screen had a RR of 1.86 (95% CI: 1.77-1.96), whereas those who tested false-positive at third screening had a RR of 2.42 (95% CI: 2.21-2.64). The RR of breast cancer at the screening test after the false-positive result was 3.95 (95% CI: 3.71-4.21), whereas it decreased to 1.25 (95% CI: 1.17-1.34) three or more screens after the false-positive result. Women with false-positive results had a twofold risk of screen-detected breast cancer compared to women with negative tests. The risk remained significantly higher three or more screens after the false-positive result. The increased risk should be considered when discussing stratified screening strategies. © 2016 The Authors. Cancer Medicine published by John Wiley & Sons Ltd.
US women's attitudes to false positive mammography results and detection of ductal carcinoma in situ: cross sectional survey

PubMed Central

Schwartz, Lisa M; Woloshin, Steven; Sox, Harold C; Fischhoff, Baruch; Welch, H Gilbert

2000-01-01

Objective To determine women's attitudes to and knowledge of both false positive mammography results and the detection of ductal carcinoma in situ after screening mammography. Design Cross sectional survey. Setting United States. Participants 479 women aged 18-97 years who did not report a history of breast cancer. Main outcome measures Attitudes to and knowledge of false positive results and the detection of ductal carcinoma in situ after screening mammography. Results Women were aware that false positive results do occur. Their median estimate of the false positive rate for 10 years of annual screening was 20% (25th percentile estimate, 10%; 75th percentile estimate, 45%). The women were highly tolerant of false positives: 63% thought that 500 or more false positives per life saved was reasonable and 37% would tolerate 10 000 or more. Women who had had a false positive result (n=76) expressed the same high tolerance: 39% would tolerate 10 000 or more false positives. 62% of women did not want to take false positive results into account when deciding about screening. Only 8% of women thought that mammography could harm a woman without breast cancer, and 94% doubted the possibility of non-progressive breast cancers. Few had heard about ductal carcinoma in situ, a cancer that may not progress, but when informed, 60% of women wanted to take into account the possibility of it being detected when deciding about screening. Conclusions Women are aware of false positives and seem to view them as an acceptable consequence of screening mammography. In contrast, most women are unaware that screening can detect cancers that may never progress but feel that such information would be relevant. Education should perhaps focus less on false positives and more on the less familiar outcome of detection of ductal carcinoma in situ. PMID:10856064
MRI criteria for MS in patients with clinically isolated syndromes.

PubMed

Montalban, X; Tintoré, M; Swanton, J; Barkhof, F; Fazekas, F; Filippi, M; Frederiksen, J; Kappos, L; Palace, J; Polman, C; Rovaris, M; de Stefano, N; Thompson, A; Yousry, T; Rovira, A; Miller, D H

2010-02-02

In recent years, criteria for the diagnosis of multiple sclerosis (MS) have changed, mainly due to the incorporation of new MRI criteria. While the new criteria are a logical step forward, they are complex and-not surprisingly-a good working knowledge of them is not always evident among neurologists and neuroradiologists. In some circumstances, several MRI examinations are needed to achieve an accurate and prompt diagnosis. This provides an incentive for continued efforts to refine the incorporation of MRI-derived information into the diagnostic workup of patients presenting with a clinically isolated syndrome. Within the European multicenter collaborative research network that studies MRI in MS (MAGNIMS), a workshop was held in London in November 2007 to review information that may simplify the existing MS diagnostic criteria, while maintaining a high specificity that is essential to minimize false positive diagnoses. New data that are now published were reviewed and discussed and together with a new proposal are integrated in this position paper.
Investigating true and false confessions within a novel experimental paradigm.

PubMed

Russano, Melissa B; Meissner, Christian A; Narchet, Fadia M; Kassin, Saul M

2005-06-01

The primary goal of the current study was to develop a novel experimental paradigm with which to study the influence of psychologically based interrogation techniques on the likelihood of true and false confessions. The paradigm involves guilty and innocent participants being accused of intentionally breaking an experimental rule, or "cheating." In the first demonstration of this paradigm, we explored the influence of two common police interrogation tactics: minimization and an explicit offer of leniency, or a "deal." Results indicated that guilty persons were more likely to confess than innocent persons, and that the use of minimization and the offer of a deal increased the rate of both true and false confessions. Police investigators are encouraged to avoid interrogation techniques that imply or directly promise leniency, as they appear to reduce the diagnostic value of any confession that is elicited.
[Evaluation of ICT malaria immunochromatographic Binax NOW ICT P.f/P.v test for rapid diagnosis of malaria in a Colombian endemic area].

PubMed

Pabón, Adriana; Alvarez, Gonzalo; Yánez, Jorge; Céspedes, Carlos; Rodríguez, Yensa; Restrepo, Angela; Blair, Silvia

2007-06-01

One of the strategies to reduce malarial morbidity and mortality is to make an early diagnosis, using simple rapid tests which are highly sensitive and specific. Furthermore, the tests must be easy to perform and understand by local people in such a way that a suitable and prompt antimalarial treatment is guaranteed. The sensitivity and specificity was determined for the immuno-chromographic malaria dipstick (ICT Pf/Pv) test for the rapid diagnosis of malaria in Turbo, Antioquia. The sample consisted of 171 patients distributed into two groups: the first group was 118 patients with acute febrile syndrome compatible with malaria to which ICT Pf/Pv and thick smears were applied simultaneously; a second group was 53 patients with positive diagnosis by thick smear, with follow-up on the 4th and 7th days after beginning treatment. Sensitivity and specificity of the ICT Pf/Pv test for Plasmodium falciparum infections were 54.2% (95%CI: 52.0-53.4%) and 93.6% (95%CI: 93.1-94.2%), respectively. In addition, for Plasmodium vivax the sensitivity and specificity were 80% (95%CI: 77.9-82.1%) and 100% (95%CI: 99.5-100%); there was a 21.4% loss of sensitivity for P. falciparum 21.4% and a 33% loss for P. vivax malaria with parasitaemias under 500 parasites/ul. For the confirmatory test, ICT Pf/Pv showed a global sensitivity of 71.6% with 20.7% false positive and 5.6% false negative results. During follow-up, ICT showed 36% and 34% false positive results for day 4 and 7, respectively. The ICT Pf/Pv test has a poor sensitivity for P. falciparum malaria and its capacity to detect parasitemias under 500 parasites/ul is minimal. As a confirmatory test, the ICT Pf/Pv has a good sensitivity for P. falciparum. Its use for patient follow-up is not recommended.
9 CFR 93.436 - Ruminants from regions of minimal risk for BSE.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 9 Animals and Animal Products 1 2010-01-01 2010-01-01 false Ruminants from regions of minimal risk for BSE. 93.436 Section 93.436 Animals and Animal Products ANIMAL AND PLANT HEALTH INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE EXPORTATION AND IMPORTATION OF ANIMALS (INCLUDING POULTRY) AND ANIMAL PRODUCTS...
9 CFR 93.436 - Ruminants from regions of minimal risk for BSE.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 9 Animals and Animal Products 1 2011-01-01 2011-01-01 false Ruminants from regions of minimal risk for BSE. 93.436 Section 93.436 Animals and Animal Products ANIMAL AND PLANT HEALTH INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE EXPORTATION AND IMPORTATION OF ANIMALS (INCLUDING POULTRY) AND ANIMAL PRODUCTS...
ROCker: accurate detection and quantification of target genes in short-read metagenomic data sets by modeling sliding-window bitscores

DOE PAGES

Orellana, Luis H.; Rodriguez-R, Luis M.; Konstantinidis, Konstantinos T.

2016-10-07

Functional annotation of metagenomic and metatranscriptomic data sets relies on similarity searches based on e-value thresholds resulting in an unknown number of false positive and negative matches. To overcome these limitations, we introduce ROCker, aimed at identifying position-specific, most-discriminant thresholds in sliding windows along the sequence of a target protein, accounting for non-discriminative domains shared by unrelated proteins. ROCker employs the receiver operating characteristic (ROC) curve to minimize false discovery rate (FDR) and calculate the best thresholds based on how simulated shotgun metagenomic reads of known composition map onto well-curated reference protein sequences and thus, differs from HMM profiles andmore » related methods. We showcase ROCker using ammonia monooxygenase (amoA) and nitrous oxide reductase (nosZ) genes, mediating oxidation of ammonia and the reduction of the potent greenhouse gas, N 2O, to inert N 2, respectively. ROCker typically showed 60-fold lower FDR when compared to the common practice of using fixed e-values. Previously uncounted ‘atypical’ nosZ genes were found to be two times more abundant, on average, than their typical counterparts in most soil metagenomes and the abundance of bacterial amoA was quantified against the highly-related particulate methane monooxygenase (pmoA). Therefore, ROCker can reliably detect and quantify target genes in short-read metagenomes.« less

ROCker: accurate detection and quantification of target genes in short-read metagenomic data sets by modeling sliding-window bitscores

DOE Office of Scientific and Technical Information (OSTI.GOV)

Orellana, Luis H.; Rodriguez-R, Luis M.; Konstantinidis, Konstantinos T.

Functional annotation of metagenomic and metatranscriptomic data sets relies on similarity searches based on e-value thresholds resulting in an unknown number of false positive and negative matches. To overcome these limitations, we introduce ROCker, aimed at identifying position-specific, most-discriminant thresholds in sliding windows along the sequence of a target protein, accounting for non-discriminative domains shared by unrelated proteins. ROCker employs the receiver operating characteristic (ROC) curve to minimize false discovery rate (FDR) and calculate the best thresholds based on how simulated shotgun metagenomic reads of known composition map onto well-curated reference protein sequences and thus, differs from HMM profiles andmore » related methods. We showcase ROCker using ammonia monooxygenase (amoA) and nitrous oxide reductase (nosZ) genes, mediating oxidation of ammonia and the reduction of the potent greenhouse gas, N 2O, to inert N 2, respectively. ROCker typically showed 60-fold lower FDR when compared to the common practice of using fixed e-values. Previously uncounted ‘atypical’ nosZ genes were found to be two times more abundant, on average, than their typical counterparts in most soil metagenomes and the abundance of bacterial amoA was quantified against the highly-related particulate methane monooxygenase (pmoA). Therefore, ROCker can reliably detect and quantify target genes in short-read metagenomes.« less
ROCker: accurate detection and quantification of target genes in short-read metagenomic data sets by modeling sliding-window bitscores

PubMed Central

2017-01-01

Abstract Functional annotation of metagenomic and metatranscriptomic data sets relies on similarity searches based on e-value thresholds resulting in an unknown number of false positive and negative matches. To overcome these limitations, we introduce ROCker, aimed at identifying position-specific, most-discriminant thresholds in sliding windows along the sequence of a target protein, accounting for non-discriminative domains shared by unrelated proteins. ROCker employs the receiver operating characteristic (ROC) curve to minimize false discovery rate (FDR) and calculate the best thresholds based on how simulated shotgun metagenomic reads of known composition map onto well-curated reference protein sequences and thus, differs from HMM profiles and related methods. We showcase ROCker using ammonia monooxygenase (amoA) and nitrous oxide reductase (nosZ) genes, mediating oxidation of ammonia and the reduction of the potent greenhouse gas, N2O, to inert N2, respectively. ROCker typically showed 60-fold lower FDR when compared to the common practice of using fixed e-values. Previously uncounted ‘atypical’ nosZ genes were found to be two times more abundant, on average, than their typical counterparts in most soil metagenomes and the abundance of bacterial amoA was quantified against the highly-related particulate methane monooxygenase (pmoA). Therefore, ROCker can reliably detect and quantify target genes in short-read metagenomes. PMID:28180325
Experimental investigation of false positive errors in auditory species occurrence surveys

USGS Publications Warehouse

Miller, David A.W.; Weir, Linda A.; McClintock, Brett T.; Grant, Evan H. Campbell; Bailey, Larissa L.; Simons, Theodore R.

2012-01-01

False positive errors are a significant component of many ecological data sets, which in combination with false negative errors, can lead to severe biases in conclusions about ecological systems. We present results of a field experiment where observers recorded observations for known combinations of electronically broadcast calling anurans under conditions mimicking field surveys to determine species occurrence. Our objectives were to characterize false positive error probabilities for auditory methods based on a large number of observers, to determine if targeted instruction could be used to reduce false positive error rates, and to establish useful predictors of among-observer and among-species differences in error rates. We recruited 31 observers, ranging in abilities from novice to expert, that recorded detections for 12 species during 180 calling trials (66,960 total observations). All observers made multiple false positive errors and on average 8.1% of recorded detections in the experiment were false positive errors. Additional instruction had only minor effects on error rates. After instruction, false positive error probabilities decreased by 16% for treatment individuals compared to controls with broad confidence interval overlap of 0 (95% CI: -46 to 30%). This coincided with an increase in false negative errors due to the treatment (26%; -3 to 61%). Differences among observers in false positive and in false negative error rates were best predicted by scores from an online test and a self-assessment of observer ability completed prior to the field experiment. In contrast, years of experience conducting call surveys was a weak predictor of error rates. False positive errors were also more common for species that were played more frequently, but were not related to the dominant spectral frequency of the call. Our results corroborate other work that demonstrates false positives are a significant component of species occurrence data collected by auditory methods. Instructing observers to only report detections they are completely certain are correct is not sufficient to eliminate errors. As a result, analytical methods that account for false positive errors will be needed, and independent testing of observer ability is a useful predictor for among-observer variation in observation error rates.
Characterisation of false-positive observations in botanical surveys

PubMed Central

2017-01-01

Errors in botanical surveying are a common problem. The presence of a species is easily overlooked, leading to false-absences; while misidentifications and other mistakes lead to false-positive observations. While it is common knowledge that these errors occur, there are few data that can be used to quantify and describe these errors. Here we characterise false-positive errors for a controlled set of surveys conducted as part of a field identification test of botanical skill. Surveys were conducted at sites with a verified list of vascular plant species. The candidates were asked to list all the species they could identify in a defined botanically rich area. They were told beforehand that their final score would be the sum of the correct species they listed, but false-positive errors counted against their overall grade. The number of errors varied considerably between people, some people create a high proportion of false-positive errors, but these are scattered across all skill levels. Therefore, a person’s ability to correctly identify a large number of species is not a safeguard against the generation of false-positive errors. There was no phylogenetic pattern to falsely observed species; however, rare species are more likely to be false-positive as are species from species rich genera. Raising the threshold for the acceptance of an observation reduced false-positive observations dramatically, but at the expense of more false negative errors. False-positive errors are higher in field surveying of plants than many people may appreciate. Greater stringency is required before accepting species as present at a site, particularly for rare species. Combining multiple surveys resolves the problem, but requires a considerable increase in effort to achieve the same sensitivity as a single survey. Therefore, other methods should be used to raise the threshold for the acceptance of a species. For example, digital data input systems that can verify, feedback and inform the user are likely to reduce false-positive errors significantly. PMID:28533972
Are special read alignment strategies necessary and cost-effective when handling sequencing reads from patient-derived tumor xenografts?

PubMed

Tso, Kai-Yuen; Lee, Sau Dan; Lo, Kwok-Wai; Yip, Kevin Y

2014-12-23

Patient-derived tumor xenografts in mice are widely used in cancer research and have become important in developing personalized therapies. When these xenografts are subject to DNA sequencing, the samples could contain various amounts of mouse DNA. It has been unclear how the mouse reads would affect data analyses. We conducted comprehensive simulations to compare three alignment strategies at different mutation rates, read lengths, sequencing error rates, human-mouse mixing ratios and sequenced regions. We also sequenced a nasopharyngeal carcinoma xenograft and a cell line to test how the strategies work on real data. We found the "filtering" and "combined reference" strategies performed better than aligning reads directly to human reference in terms of alignment and variant calling accuracies. The combined reference strategy was particularly good at reducing false negative variants calls without significantly increasing the false positive rate. In some scenarios the performance gain of these two special handling strategies was too small for special handling to be cost-effective, but it was found crucial when false non-synonymous SNVs should be minimized, especially in exome sequencing. Our study systematically analyzes the effects of mouse contamination in the sequencing data of human-in-mouse xenografts. Our findings provide information for designing data analysis pipelines for these data.
Clinical Data as an Adjunct to Ultrasound Reduces the False-Negative Malignancy Rate in BI-RADS 3 Breast Lesions

PubMed Central

Ackermann, S.; Schoenenberger, C.-A.; Zanetti-Dällenbach, R.

2016-01-01

Purpose: Ultrasound (US) is a well-established diagnostic procedure for breast examination. We investigated the malignancy rate in solid breast lesions according to their BI-RADS classification with a particular focus on false-negative BI-RADS 3 lesions. We examined whether patient history and clinical findings could provide additional information that would help determine further diagnostic steps in breast lesions. Materials and Methods: We conducted a retrospective study by exploring US BI-RADS in 1469 breast lesions of 1201 patients who underwent minimally invasive breast biopsy (MIBB) from January 2002 to December 2011. Results: The overall sensitivity and specificity of BI-RADS classification was 97.4% and 66.4%, respectively, with a positive (PPV) and negative predictive value (NPV) of 65% and 98%, respectively. In 506 BI-RADS 3 lesions, histology revealed 15 malignancies (2.4% malignancy rate), which corresponds to a false-negative rate (FNR) of 2.6%. Clinical evaluation and patient requests critically influenced the further diagnostic procedure, thereby prevailing over the recommendation given by the BI-RADS 3 classification. Conclusion: Clinical criteria including age, family and personal history, clinical examination, mammography and patient choice ensure adequate diagnostic procedures such as short-term follow-up or MIBB in patients with lesions classified as US-BI-RADS 3. PMID:27689181
Kepler Certified False Positive Table

NASA Technical Reports Server (NTRS)

Bryson, Stephen T.; Batalha, Natalie Marie; Colon, Knicole Dawn; Coughlin, Jeffrey Langer; Haas, Michael R.; Henze, Chris; Huber, Daniel; Morton, Tim; Rowe, Jason Frank; Mullally, Susan Elizabeth;

2017-01-01

This document describes the Kepler Certied False Positive table hosted at the Exoplanet Archive1, herein referred to as the CFP table. This table is the result of detailed examination by the Kepler False Positive Working Group (FPWG) of declared false positives in the Kepler Object of Interest (KOI) tables (see, for example, Batalha et al. (2012); Burke et al.(2014); Rowe et al. (2015); Mullally et al. (2015); Coughlin et al. (2015b)) at the Exoplanet Archive. A KOI is considered a false positive if it is not due to a planet orbiting the KOI's target star. The CFP table contains all KOIs in the Exoplanet Archive cumulative KOI table. The purpose of the CFP table is to provide a list of certified false positive KOIs. A KOI is certified as a false positive when, in the judgement of the FPWG, there is no plausible planetary interpretation of the observational evidence, which we summarize by saying that the evidence for a false positive is compelling. This certification process involves detailed examination using all available data for each KOI, establishing a high-reliability ground truth set. The CFP table can be used to estimate the reliability of, for example, the KOI tables which are created using only Kepler photometric data, so the disposition of individual KOIs may differ in the KOI and CFP tables. Follow-up observers may find the CFP table useful to avoid observing false positives.

Cumulative risk of false positive test in relation to breast symptoms in mammography screening: a historical prospective cohort study.

PubMed

Singh, Deependra; Pitkäniemi, Janne; Malila, Nea; Anttila, Ahti

2016-09-01

Mammography has been found effective as the primary screening test for breast cancer. We estimated the cumulative probability of false positive screening test results with respect to symptom history reported at screen. A historical prospective cohort study was done using individual screening data from 413,611 women aged 50-69 years with 2,627,256 invitations for mammography screening between 1992 and 2012 in Finland. Symptoms (lump, retraction, and secretion) were reported at 56,805 visits, and 48,873 visits resulted in a false positive mammography result. Generalized linear models were used to estimate the probability of at least one false positive test and true positive at screening visits. The estimates were compared among women with and without symptoms history. The estimated cumulative probabilities were 18 and 6 % for false positive and true positive results, respectively. In women with a history of a lump, the cumulative probabilities of false positive test and true positive were 45 and 16 %, respectively, compared to 17 and 5 % with no reported lump. In women with a history of any given symptom, the cumulative probabilities of false positive test and true positive were 38 and 13 %, respectively. Likewise, women with a history of a 'lump and retraction' had the cumulative false positive probability of 56 %. The study showed higher cumulative risk of false positive tests and more cancers detected in women who reported symptoms compared to women who did not report symptoms at screen. The risk varies substantially, depending on symptom types and characteristics. Information on breast symptoms influences the balance of absolute benefits and harms of screening.
Detecting false positives in multielement designs: implications for brief assessments.

PubMed

Bartlett, Sara M; Rapp, John T; Henrickson, Marissa L

2011-11-01

The authors assessed the extent to which multielement designs produced false positives using continuous duration recording (CDR) and interval recording with 10-s and 1-min interval sizes. Specifically, they created 6,000 graphs with multielement designs that varied in the number of data paths, and the number of data points per data path, using a random number generator. In Experiment 1, the authors visually analyzed the graphs for the occurrence of false positives. Results indicated that graphs depicting only two sessions for each condition (e.g., a control condition plotted with multiple test conditions) produced the highest percentage of false positives for CDR and interval recording with 10-s and 1-min intervals. Conversely, graphs with four or five sessions for each condition produced the lowest percentage of false positives for each method. In Experiment 2, they applied two new rules, which were intended to decrease false positives, to each graph that depicted a false positive in Experiment 1. Results showed that application of new rules decreased false positives to less than 5% for all of the graphs except for those with two data paths and two data points per data path. Implications for brief assessments are discussed.
Response time as a discriminator between true- and false-positive responses in suprathreshold perimetry.

PubMed

Artes, Paul H; McLeod, David; Henson, David B

2002-01-01

To report on differences between the latency distributions of responses to stimuli and to false-positive catch trials in suprathreshold perimetry. To describe an algorithm for defining response time windows and to report on its performance in discriminating between true- and false-positive responses on the basis of response time (RT). A sample of 435 largely inexperienced patients underwent suprathreshold visual field examination on a perimeter that was modified to record RTs. Data were analyzed from 60,500 responses to suprathreshold stimuli and from 523 false-positive responses to catch trials. False-positive responses had much more variable latencies than responses to suprathreshold stimuli. An algorithm defining RT windows on the basis of z-transformed individual latency samples correctly identified more than 70% of false-positive responses to catch trials, whereas fewer than 3% of responses to suprathreshold stimuli were classified as false-positive responses. Latency analysis can be used to detect a substantial proportion of false-positive responses in suprathreshold perimetry. Rejection of such responses may increase the reliability of visual field screening by reducing variability and bias in a small but clinically important proportion of patients.
Mitosis detection using generic features and an ensemble of cascade adaboosts.

PubMed

Tek, F Boray

2013-01-01

Mitosis count is one of the factors that pathologists use to assess the risk of metastasis and survival of the patients, which are affected by the breast cancer. We investigate an application of a set of generic features and an ensemble of cascade adaboosts to the automated mitosis detection. Calculation of the features rely minimally on object-level descriptions and thus require minimal segmentation. The proposed work was developed and tested on International Conference on Pattern Recognition (ICPR) 2012 mitosis detection contest data. We plotted receiver operating characteristics curves of true positive versus false positive rates; calculated recall, precision, F-measure, and region overlap ratio measures. WE TESTED OUR FEATURES WITH TWO DIFFERENT CLASSIFIER CONFIGURATIONS: 1) An ensemble of single adaboosts, 2) an ensemble of cascade adaboosts. On the ICPR 2012 mitosis detection contest evaluation, the cascade ensemble scored 54, 62.7, and 58, whereas the non-cascade version scored 68, 28.1, and 39.7 for the recall, precision, and F-measure measures, respectively. Mostly used features in the adaboost classifier rules were a shape-based feature, which counted granularity and a color-based feature, which relied on Red, Green, and Blue channel statistics. The features, which express the granular structure and color variations, are found useful for mitosis detection. The ensemble of adaboosts performs better than the individual adaboost classifiers. Moreover, the ensemble of cascaded adaboosts was better than the ensemble of single adaboosts for mitosis detection.
Prescription drugs associated with false-positive results when using faecal immunochemical tests for colorectal cancer screening.

PubMed

Ibáñez-Sanz, Gemma; Garcia, Montse; Rodríguez-Moranta, Francisco; Binefa, Gemma; Gómez-Matas, Javier; Domènech, Xènia; Vidal, Carmen; Soriano, Antonio; Moreno, Víctor

2016-10-01

The most common side effect in population screening programmes is a false-positive result which leads to unnecessary risks and costs. To identify factors associated with false-positive results in a colorectal cancer screening programme with the faecal immunochemical test (FIT). Cross-sectional study of 472 participants with a positive FIT who underwent colonoscopy for confirmation of diagnosis between 2013 and 2014. A false-positive result was defined as having a positive FIT (≥20μg haemoglobin per gram of faeces) and follow-up colonoscopy without intermediate/high-risk lesions or cancer. Women showed a two-fold increased likelihood of a false-positive result compared with men (adjusted OR, 2.3; 95%CI, 1.5-3.4), but no female-specific factor was identified. The other variables associated with a false-positive result were successive screening (adjusted OR, 1.5; 95%CI, 1.0-2.2), anal disorders (adjusted OR, 3.1; 95%CI, 2.1-4.5) and the use of proton pump inhibitors (adjusted OR, 1.8; 95%CI, 1.1-2.9). Successive screening and proton pump inhibitor use were associated with FP in men. None of the other drugs were related to a false-positive FIT. Concurrent use of proton pump inhibitors at the time of FIT might increase the likelihood of a false-positive result. Further investigation is needed to determine whether discontinuing them could decrease the false-positive rate. Copyright © 2016 Editrice Gastroenterologica Italiana S.r.l. Published by Elsevier Ltd. All rights reserved.
46 CFR 108.404 - Selection of fire detection system.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 4 2010-10-01 2010-10-01 false Selection of fire detection system. 108.404 Section 108... DESIGN AND EQUIPMENT Fire Extinguishing Systems § 108.404 Selection of fire detection system. (a) If a... space. (b) The fire detection system must be designed to minimize false alarms. ...
45 CFR 690.110 - Expedited review procedures for certain kinds of research involving no more than minimal risk...

Code of Federal Regulations, 2012 CFR

2012-10-01

... 45 Public Welfare 3 2012-10-01 2012-10-01 false Expedited review procedures for certain kinds of research involving no more than minimal risk, and for minor changes in approved research. 690.110 Section 690.110 Public Welfare Regulations Relating to Public Welfare (Continued) NATIONAL SCIENCE FOUNDATION...
45 CFR 690.110 - Expedited review procedures for certain kinds of research involving no more than minimal risk...

Code of Federal Regulations, 2013 CFR

2013-10-01

... 45 Public Welfare 3 2013-10-01 2013-10-01 false Expedited review procedures for certain kinds of research involving no more than minimal risk, and for minor changes in approved research. 690.110 Section 690.110 Public Welfare Regulations Relating to Public Welfare (Continued) NATIONAL SCIENCE FOUNDATION...
45 CFR 690.110 - Expedited review procedures for certain kinds of research involving no more than minimal risk...

Code of Federal Regulations, 2014 CFR

2014-10-01

... 45 Public Welfare 3 2014-10-01 2014-10-01 false Expedited review procedures for certain kinds of research involving no more than minimal risk, and for minor changes in approved research. 690.110 Section 690.110 Public Welfare Regulations Relating to Public Welfare (Continued) NATIONAL SCIENCE FOUNDATION...
50 CFR 14.32 - Permits to import or export wildlife at nondesignated port to minimize deterioration or loss.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 50 Wildlife and Fisheries 1 2010-10-01 2010-10-01 false Permits to import or export wildlife at nondesignated port to minimize deterioration or loss. 14.32 Section 14.32 Wildlife and Fisheries UNITED STATES FISH AND WILDLIFE SERVICE, DEPARTMENT OF THE INTERIOR TAKING, POSSESSION, TRANSPORTATION, SALE...
50 CFR 14.32 - Permits to import or export wildlife at nondesignated port to minimize deterioration or loss.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 50 Wildlife and Fisheries 1 2013-10-01 2013-10-01 false Permits to import or export wildlife at nondesignated port to minimize deterioration or loss. 14.32 Section 14.32 Wildlife and Fisheries UNITED STATES FISH AND WILDLIFE SERVICE, DEPARTMENT OF THE INTERIOR TAKING, POSSESSION, TRANSPORTATION, SALE...
50 CFR 14.32 - Permits to import or export wildlife at nondesignated port to minimize deterioration or loss.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 50 Wildlife and Fisheries 1 2012-10-01 2012-10-01 false Permits to import or export wildlife at nondesignated port to minimize deterioration or loss. 14.32 Section 14.32 Wildlife and Fisheries UNITED STATES FISH AND WILDLIFE SERVICE, DEPARTMENT OF THE INTERIOR TAKING, POSSESSION, TRANSPORTATION, SALE...
50 CFR 14.32 - Permits to import or export wildlife at nondesignated port to minimize deterioration or loss.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 50 Wildlife and Fisheries 1 2011-10-01 2011-10-01 false Permits to import or export wildlife at nondesignated port to minimize deterioration or loss. 14.32 Section 14.32 Wildlife and Fisheries UNITED STATES FISH AND WILDLIFE SERVICE, DEPARTMENT OF THE INTERIOR TAKING, POSSESSION, TRANSPORTATION, SALE...

50 CFR 14.32 - Permits to import or export wildlife at nondesignated port to minimize deterioration or loss.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 50 Wildlife and Fisheries 1 2014-10-01 2014-10-01 false Permits to import or export wildlife at nondesignated port to minimize deterioration or loss. 14.32 Section 14.32 Wildlife and Fisheries UNITED STATES FISH AND WILDLIFE SERVICE, DEPARTMENT OF THE INTERIOR TAKING, POSSESSION, TRANSPORTATION, SALE...
34 CFR 97.406 - Research involving greater than minimal risk and no prospect of direct benefit to individual...

Code of Federal Regulations, 2010 CFR

2010-07-01

... subject's disorder or condition. 97.406 Section 97.406 Education Office of the Secretary, Department of Education PROTECTION OF HUMAN SUBJECTS Additional ED Protections for Children Who Are Subjects in Research... 34 Education 1 2010-07-01 2010-07-01 false Research involving greater than minimal risk and no...
9 CFR 93.436 - Ruminants from regions of minimal risk for BSE.

Code of Federal Regulations, 2013 CFR

2013-01-01

... each animal's right hip, high on the tail-head (over the junction of the sacral and first cocygeal... 9 Animals and Animal Products 1 2013-01-01 2013-01-01 false Ruminants from regions of minimal risk for BSE. 93.436 Section 93.436 Animals and Animal Products ANIMAL AND PLANT HEALTH INSPECTION SERVICE...
9 CFR 93.436 - Ruminants from regions of minimal risk for BSE.

Code of Federal Regulations, 2012 CFR

2012-01-01

... each animal's right hip, high on the tail-head (over the junction of the sacral and first cocygeal... 9 Animals and Animal Products 1 2012-01-01 2012-01-01 false Ruminants from regions of minimal risk for BSE. 93.436 Section 93.436 Animals and Animal Products ANIMAL AND PLANT HEALTH INSPECTION SERVICE...
Does a minimally invasive approach affect positioning of components in unicompartmental knee arthroplasty? Early results with survivorship analysis.

PubMed

Cool, Steve; Victor, Jan; De Baets, Thierry

2006-12-01

Fifty unicompartmental knee arthroplasties (UKAs) were performed through a minimally invasive approach and were reviewed with an average follow-up of 3.7 years. This technique leads to reduced access to surgical landmarks. The purpose of this study was to evaluate whether correct component positioning is possible through this less invasive approach. Component positioning, femorotibial alignment and early outcomes were evaluated. We observed perfect tibial component position, but femoral component position was less consistent, especially in the sagittal plane. Femorotibial alignment in the coronal plane was within 2.5 degrees of the desired axis for 80% of the cases. Femoral component position in the sagittal plane was within a 10 degrees range of the ideal for 70% of the cases. The mean IKS Knee Function Score and Knee Score were 89/100 and 91/100 respectively. We observed two polyethylene dislocations, and one revision was performed for progressive patellofemoral arthrosis. According to our data, minimally invasive UKA does not conflict with component positioning although a learning curve needs to be respected, with femoral component positioning as the major obstacle.
Accurate decisions in an uncertain world: collective cognition increases true positives while decreasing false positives.

PubMed

Wolf, Max; Kurvers, Ralf H J M; Ward, Ashley J W; Krause, Stefan; Krause, Jens

2013-04-07

In a wide range of contexts, including predator avoidance, medical decision-making and security screening, decision accuracy is fundamentally constrained by the trade-off between true and false positives. Increased true positives are possible only at the cost of increased false positives; conversely, decreased false positives are associated with decreased true positives. We use an integrated theoretical and experimental approach to show that a group of decision-makers can overcome this basic limitation. Using a mathematical model, we show that a simple quorum decision rule enables individuals in groups to simultaneously increase true positives and decrease false positives. The results from a predator-detection experiment that we performed with humans are in line with these predictions: (i) after observing the choices of the other group members, individuals both increase true positives and decrease false positives, (ii) this effect gets stronger as group size increases, (iii) individuals use a quorum threshold set between the average true- and false-positive rates of the other group members, and (iv) individuals adjust their quorum adaptively to the performance of the group. Our results have broad implications for our understanding of the ecology and evolution of group-living animals and lend themselves for applications in the human domain such as the design of improved screening methods in medical, forensic, security and business applications.
Accurate decisions in an uncertain world: collective cognition increases true positives while decreasing false positives

PubMed Central

Wolf, Max; Kurvers, Ralf H. J. M.; Ward, Ashley J. W.; Krause, Stefan; Krause, Jens

2013-01-01

In a wide range of contexts, including predator avoidance, medical decision-making and security screening, decision accuracy is fundamentally constrained by the trade-off between true and false positives. Increased true positives are possible only at the cost of increased false positives; conversely, decreased false positives are associated with decreased true positives. We use an integrated theoretical and experimental approach to show that a group of decision-makers can overcome this basic limitation. Using a mathematical model, we show that a simple quorum decision rule enables individuals in groups to simultaneously increase true positives and decrease false positives. The results from a predator-detection experiment that we performed with humans are in line with these predictions: (i) after observing the choices of the other group members, individuals both increase true positives and decrease false positives, (ii) this effect gets stronger as group size increases, (iii) individuals use a quorum threshold set between the average true- and false-positive rates of the other group members, and (iv) individuals adjust their quorum adaptively to the performance of the group. Our results have broad implications for our understanding of the ecology and evolution of group-living animals and lend themselves for applications in the human domain such as the design of improved screening methods in medical, forensic, security and business applications. PMID:23407830
Categorizing mistaken false positives in regulation of human and environmental health.

PubMed

Hansen, Steffen Foss; Krayer von Krauss, Martin P; Tickner, Joel A

2007-02-01

One of the concerns often voiced by critics of the precautionary principle is that a widespread regulatory application of the principle will lead to a large number of false positives (i.e., over-regulation of minor risks and regulation of nonexisting risks). The present article proposes a general definition of a regulatory false positive, and seeks to identify case studies that can be considered authentic regulatory false positives. Through a comprehensive review of the science policy literature for proclaimed false positives and interviews with authorities on regulation and the precautionary principle we identified 88 cases. Following a detailed analysis of these cases, we found that few of the cases mentioned in the literature can be considered to be authentic false positives. As a result, we have developed a number of different categories for these cases of "mistaken false positives," including: real risks, "The jury is still out," nonregulated proclaimed risks, "Too narrow a definition of risk," and risk-risk tradeoffs. These categories are defined and examples are presented in order to illustrate their key characteristics. On the basis of our analysis, we were able to identify only four cases that could be defined as regulatory false positives in the light of today's knowledge and recognized uncertainty: the Southern Corn Leaf Blight, the Swine Flu, Saccharin, and Food Irradiation in relation to consumer health. We conclude that concerns about false positives do not represent a reasonable argument against future application of the precautionary principle.
Predictive value of autoantibody testing for validating self-reported diagnoses of rheumatoid arthritis in the Women's Health Initiative.

PubMed

Walitt, Brian; Mackey, Rachel; Kuller, Lewis; Deane, Kevin D; Robinson, William; Holers, V Michael; Chang, Yue-Fang; Moreland, Larry

2013-05-01

Rheumatoid arthritis (RA) research using large databases is limited by insufficient case validity. Of 161,808 postmenopausal women in the Women's Health Initiative, 15,691 (10.2%) reported having RA, far higher than the expected 1% population prevalence. Since chart review for confirmation of an RA diagnosis is impractical in large cohort studies, the current study (2009-2011) tested the ability of baseline serum measurements of rheumatoid factor and anti-cyclic citrullinated peptide antibodies, second-generation assay (anti-CCP2), to identify physician-validated RA among the chart-review study participants with self-reported RA (n = 286). Anti-CCP2 positivity had the highest positive predictive value (PPV) (80.0%), and rheumatoid factor positivity the lowest (44.6%). Together, use of disease-modifying antirheumatic drugs and anti-CCP2 positivity increased PPV to 100% but excluded all seronegative cases (approximately 15% of all RA cases). Case definitions inclusive of seronegative cases had PPVs between 59.6% and 63.6%. False-negative results were minimized in these test definitions, as evidenced by negative predictive values of approximately 90%. Serological measurements, particularly measurement of anti-CCP2, improved the test characteristics of RA case definitions in the Women's Health Initiative.
An analysis of false positive reactions occurring with the Captia Syph G EIA.

PubMed Central

Ross, J; Moyes, A; Young, H; McMillan, A

1991-01-01

AIM--The Captia Syph G enzyme immuno assay (EAI) offers the potential for the rapid automated detection of syphilis antibodies. This study was designed to assess the role of other sexually transmitted diseases (STDs) in producing false positive reactions in the Captia Syph G EIA. The role of rheumatoid factor (RF) as a potential source of false positives was also analysed. METHODS--Patients who attended a genitourinary medicine (GUM) department and gave a false positive reaction with the EIA between 1988 and 1990 were compared with women undergoing antenatal testing and with the control clinic population (EIA negative) over the same time period. The incidence of sexually transmitted disease (STD) in the clinic population and the false positive reactors was measured in relation to gonorrhoea, chlamydia, genital warts, candidiasis, "other conditions not requiring treatment" and "other conditions requiring treatment." Male: female sex ratios were also compared. Ninety two RF positive sera were analysed with the EIA. RESULTS--The rate of false positive reactions did not differ with respect to the diagnosis within the GUM clinic population. The antenatal group of women, however, had a lower incidence of false positive reactions than the GUM clinic group. No RF positive sera were positive on Captia Syph G EIA testing. CONCLUSIONS--There is no cross reaction between Captia Syph G EIA and any specific STD or with RF positive sera. The lower incidence of false positive reactions in antenatal women is unexplained but may be related to physiological changes associated with pregnancy. PMID:1743715
Clinical value of polymerase chain reaction in the diagnosis of joint tuberculosis by detecting the DNA of Mycobacterium tuberculosis.

PubMed

Sun, Yong-sheng; Lou, Si-quan; Wen, Jian-min; Lv, Wei-xin; Jiao, Chang-geng; Yang, Su-min; Xu, Hai-bin

2011-02-01

To assess the clinical value of polymerase chain reaction (PCR) in the diagnosis and differential diagnosis of joint tuberculosis (TB). PCR was used blindly to detect the DNA of Mycobacterium tuberculosis (M.TB) in five specimens of M.TB, 5 of BCG, and 10 of other bacteria. Then, M. TB in 98 samples from patients with joint TB and 100 samples from patients with non-tubercular joint disorders were detected by PCR, acid-fast staining and culture,. The sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of PCR were calculated. The χ2 test was used for statistical analysis of the frequency of various factors. At the same time, some problems with PCR were also systematically analyzed. (1) In the "standard samples", both M. TB and BCG showed positive while other bacteria were negative. (2) In 98 cases from patients with joint TB, 81 were positive by PCR, 6 by acid-fast staining, and 17 by culture. In 100 cases from patients with non-tuberculous joint disorders, 9 were positive by PCR, and none by either acid-fast staining or culture. Sensitivity, specificity, accuracy, positive and negative predictive value of PCR were 82.65% (81/98), 91.00% (91/100), 86.87% (172/198), 90.00% (81/90) and 84.26% (91/108), respectively. (3) The positive rates for PCR, acid-fast staining and culture in detection of M. TB were 82.65% (81/98), 6.12% (6/98), and 17.34% (17/98), respectively. There were statistically significant differences between the three methods (P < 0.001). (4) The process of PCR is automatic, and can be completed within 3 to 6 hours, whereas 4 to 8 weeks are required for the conventional culture of M. TB. PCR is a sensitive, specific, rapid, simple and minimally invasive method for detection of M. TB in samples from joint TB, and can play an important role in early and rapid diagnosis and differential diagnosis of joint TB. But it also has some limitations, such as false positivity and false negativity. © 2011 Tianjin Hospital and Blackwell Publishing Asia Pty Ltd.
Minimal position-velocity uncertainty wave packets in relativistic and non-relativistic quantum mechanics

NASA Astrophysics Data System (ADS)

Al-Hashimi, M. H.; Wiese, U.-J.

2009-12-01

We consider wave packets of free particles with a general energy-momentum dispersion relation E(p). The spreading of the wave packet is determined by the velocity v=∂pE. The position-velocity uncertainty relation ΔxΔv⩾12|<∂p2E>| is saturated by minimal uncertainty wave packets Φ(p)=Aexp(-αE(p)+βp). In addition to the standard minimal Gaussian wave packets corresponding to the non-relativistic dispersion relation E(p)=p2/2m, analytic calculations are presented for the spreading of wave packets with minimal position-velocity uncertainty product for the lattice dispersion relation E(p)=-cos(pa)/ma2 as well as for the relativistic dispersion relation E(p)=p2+m2. The boost properties of moving relativistic wave packets as well as the propagation of wave packets in an expanding Universe are also discussed.
Frequency of false positive rapid HIV serologic tests in African men and women receiving PrEP for HIV prevention: implications for programmatic roll-out of biomedical interventions.

PubMed

Ndase, Patrick; Celum, Connie; Kidoguchi, Lara; Ronald, Allan; Fife, Kenneth H; Bukusi, Elizabeth; Donnell, Deborah; Baeten, Jared M

2015-01-01

Rapid HIV assays are the mainstay of HIV testing globally. Delivery of effective biomedical HIV prevention strategies such as antiretroviral pre-exposure prophylaxis (PrEP) requires periodic HIV testing. Because rapid tests have high (>95%) but imperfect specificity, they are expected to generate some false positive results. We assessed the frequency of true and false positive rapid results in the Partners PrEP Study, a randomized, placebo-controlled trial of PrEP. HIV testing was performed monthly using 2 rapid tests done in parallel with HIV enzyme immunoassay (EIA) confirmation following all positive rapid tests. A total of 99,009 monthly HIV tests were performed; 98,743 (99.7%) were dual-rapid HIV negative. Of the 266 visits with ≥1 positive rapid result, 99 (37.2%) had confirmatory positive EIA results (true positives), 155 (58.3%) had negative EIA results (false positives), and 12 (4.5%) had discordant EIA results. In the active PrEP arms, over two-thirds of visits with positive rapid test results were false positive results (69.2%, 110 of 159), although false positive results occurred at <1% (110/65,945) of total visits. When HIV prevalence or incidence is low due to effective HIV prevention interventions, rapid HIV tests result in a high number of false relative to true positive results, although the absolute number of false results will be low. Program roll-out for effective interventions should plan for quality assurance of HIV testing, mechanisms for confirmatory HIV testing, and counseling strategies for persons with positive rapid test results.
A ROC-based feature selection method for computer-aided detection and diagnosis

NASA Astrophysics Data System (ADS)

Wang, Songyuan; Zhang, Guopeng; Liao, Qimei; Zhang, Junying; Jiao, Chun; Lu, Hongbing

2014-03-01

Image-based computer-aided detection and diagnosis (CAD) has been a very active research topic aiming to assist physicians to detect lesions and distinguish them from benign to malignant. However, the datasets fed into a classifier usually suffer from small number of samples, as well as significantly less samples available in one class (have a disease) than the other, resulting in the classifier's suboptimal performance. How to identifying the most characterizing features of the observed data for lesion detection is critical to improve the sensitivity and minimize false positives of a CAD system. In this study, we propose a novel feature selection method mR-FAST that combines the minimal-redundancymaximal relevance (mRMR) framework with a selection metric FAST (feature assessment by sliding thresholds) based on the area under a ROC curve (AUC) generated on optimal simple linear discriminants. With three feature datasets extracted from CAD systems for colon polyps and bladder cancer, we show that the space of candidate features selected by mR-FAST is more characterizing for lesion detection with higher AUC, enabling to find a compact subset of superior features at low cost.
Experimental investigation of observation error in anuran call surveys

USGS Publications Warehouse

McClintock, B.T.; Bailey, L.L.; Pollock, K.H.; Simons, T.R.

2010-01-01

Occupancy models that account for imperfect detection are often used to monitor anuran and songbird species occurrence. However, presenceabsence data arising from auditory detections may be more prone to observation error (e.g., false-positive detections) than are sampling approaches utilizing physical captures or sightings of individuals. We conducted realistic, replicated field experiments using a remote broadcasting system to simulate simple anuran call surveys and to investigate potential factors affecting observation error in these studies. Distance, time, ambient noise, and observer abilities were the most important factors explaining false-negative detections. Distance and observer ability were the best overall predictors of false-positive errors, but ambient noise and competing species also affected error rates for some species. False-positive errors made up 5 of all positive detections, with individual observers exhibiting false-positive rates between 0.5 and 14. Previous research suggests false-positive errors of these magnitudes would induce substantial positive biases in standard estimators of species occurrence, and we recommend practices to mitigate for false positives when developing occupancy monitoring protocols that rely on auditory detections. These recommendations include additional observer training, limiting the number of target species, and establishing distance and ambient noise thresholds during surveys. ?? 2010 The Wildlife Society.
Memory for media: investigation of false memories for negatively and positively charged public events.

PubMed

Porter, Stephen; Taylor, Kristian; Ten Brinke, Leanne

2008-01-01

Despite a large body of false memory research, little has addressed the potential influence of an event's emotional content on susceptibility to false recollections. The Paradoxical Negative Emotion (PNE) hypothesis predicts that negative emotion generally facilitates memory but also heightens susceptibility to false memories. Participants were asked whether they could recall 20 "widely publicised" public events (half fictitious) ranging in emotional valence, with or without visual cues. Participants recalled a greater number of true negative events (M=3.31/5) than true positive (M=2.61/5) events. Nearly everyone (95%) came to recall at least one false event (M=2.15 false events recalled). Further, more than twice as many participants recalled any false negative (90%) compared to false positive (41.7%) events. Negative events, in general, were associated with more detailed memories and false negative event memories were more detailed than false positive event memories. Higher dissociation scores were associated with false recollections of negative events, specifically.
Application of quadratic optimization to supersonic inlet control.

NASA Technical Reports Server (NTRS)

Lehtinen, B.; Zeller, J. R.

1972-01-01

This paper describes the application of linear stochastic optimal control theory to the design of the control system for the air intake, the inlet, of a supersonic air-breathing propulsion system. The controls must maintain a stable inlet shock position in the presence of random airflow disturbances and prevent inlet unstart. Two different linear time invariant controllers are developed. One is designed to minimize a nonquadratic index, the expected frequency of inlet unstart, and the other is designed to minimize the mean square value of inlet shock motion. The quadratic equivalence principle is used to obtain a linear controller that minimizes the nonquadratic index. The two controllers are compared on the basis of unstart prevention, control effort requirements, and frequency response. It is concluded that while controls designed to minimize unstarts are desirable in that the index minimized is physically meaningful, computation time required is longer than for the minimum mean square shock position approach. The simpler minimum mean square shock position solution produced expected unstart frequency values which were not significantly larger than those of the nonquadratic solution.
Generalized site occupancy models allowing for false positive and false negative errors

USGS Publications Warehouse

Royle, J. Andrew; Link, W.A.

2006-01-01

Site occupancy models have been developed that allow for imperfect species detection or ?false negative? observations. Such models have become widely adopted in surveys of many taxa. The most fundamental assumption underlying these models is that ?false positive? errors are not possible. That is, one cannot detect a species where it does not occur. However, such errors are possible in many sampling situations for a number of reasons, and even low false positive error rates can induce extreme bias in estimates of site occupancy when they are not accounted for. In this paper, we develop a model for site occupancy that allows for both false negative and false positive error rates. This model can be represented as a two-component finite mixture model and can be easily fitted using freely available software. We provide an analysis of avian survey data using the proposed model and present results of a brief simulation study evaluating the performance of the maximum-likelihood estimator and the naive estimator in the presence of false positive errors.
Minimizing liability during internal investigations.

PubMed

Morris, Cole

2010-01-01

Today's security professional must appreciate the potential landmines in any investigative effort and work collaboratively with others to minimize liability risks, the author points out. In this article he examines six civil torts that commonly arise from unprofessionally planned or poorly executed internal investigations-defamation, false imprisonment. intentional infliction of emotional distress, assault and battery, invasion of privacy, and malicious prosecution and abuse of process.
45 CFR 46.110 - Expedited review procedures for certain kinds of research involving no more than minimal risk...

Code of Federal Regulations, 2014 CFR

2014-10-01

... 45 Public Welfare 1 2014-10-01 2014-10-01 false Expedited review procedures for certain kinds of research involving no more than minimal risk, and for minor changes in approved research. 46.110 Section 46.110 Public Welfare Department of Health and Human Services GENERAL ADMINISTRATION PROTECTION OF HUMAN...

45 CFR 46.110 - Expedited review procedures for certain kinds of research involving no more than minimal risk...

Code of Federal Regulations, 2011 CFR

2011-10-01

... 45 Public Welfare 1 2011-10-01 2011-10-01 false Expedited review procedures for certain kinds of research involving no more than minimal risk, and for minor changes in approved research. 46.110 Section 46.110 Public Welfare DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL ADMINISTRATION PROTECTION OF HUMAN...
45 CFR 46.110 - Expedited review procedures for certain kinds of research involving no more than minimal risk...

Code of Federal Regulations, 2012 CFR

2012-10-01

... 45 Public Welfare 1 2012-10-01 2012-10-01 false Expedited review procedures for certain kinds of research involving no more than minimal risk, and for minor changes in approved research. 46.110 Section 46.110 Public Welfare DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL ADMINISTRATION PROTECTION OF HUMAN...
45 CFR 46.110 - Expedited review procedures for certain kinds of research involving no more than minimal risk...

Code of Federal Regulations, 2013 CFR

2013-10-01

... 45 Public Welfare 1 2013-10-01 2013-10-01 false Expedited review procedures for certain kinds of research involving no more than minimal risk, and for minor changes in approved research. 46.110 Section 46.110 Public Welfare DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL ADMINISTRATION PROTECTION OF HUMAN...
Internet Civil Defense: Feasibility Study

DTIC Science & Technology

2002-12-09

quell spread of false rumors that induce fear. Summary: Internet Civil Defense can help to manage fear in various ways. We can continuously poll...timely information to minimize rumors and accelerate recovery from disasters. ICD will create an “umbrella” framework to raise the overall...information to minimize rumors and accelerate recovery from disasters. Overall, ICD will collect and deliver actionable information to enhance public
10 CFR 745.110 - Expedited review procedures for certain kinds of research involving no more than minimal risk...

Code of Federal Regulations, 2011 CFR

2011-01-01

... adopt a method for keeping all members advised of research proposals which have been approved under the... 10 Energy 4 2011-01-01 2011-01-01 false Expedited review procedures for certain kinds of research involving no more than minimal risk, and for minor changes in approved research. 745.110 Section 745.110...
10 CFR 745.110 - Expedited review procedures for certain kinds of research involving no more than minimal risk...

Code of Federal Regulations, 2010 CFR

2010-01-01

... adopt a method for keeping all members advised of research proposals which have been approved under the... 10 Energy 4 2010-01-01 2010-01-01 false Expedited review procedures for certain kinds of research involving no more than minimal risk, and for minor changes in approved research. 745.110 Section 745.110...
22 CFR 3.6 - Procedure to be followed by employees in depositing gifts of more than minimal value and...

Code of Federal Regulations, 2010 CFR

2010-04-01

... 22 Foreign Relations 1 2010-04-01 2010-04-01 false Procedure to be followed by employees in depositing gifts of more than minimal value and reporting acceptance of travel or travel expenses. 3.6 Section 3.6 Foreign Relations DEPARTMENT OF STATE GENERAL GIFTS AND DECORATIONS FROM FOREIGN GOVERNMENTS...
Comparison of 4th-Generation HIV Antigen/Antibody Combination Assay With 3rd-Generation HIV Antibody Assays for the Occurrence of False-Positive and False-Negative Results.

PubMed

Muthukumar, Alagarraju; Alatoom, Adnan; Burns, Susan; Ashmore, Jerry; Kim, Anne; Emerson, Brian; Bannister, Edward; Ansari, M Qasim

2015-01-01

To assess the false-positive and false-negative rates of a 4th-generation human immunodeficiency virus (HIV) assay, the Abbott ARCHITECT, vs 2 HIV 3rd-generation assays, the Siemens Centaur and the Ortho-Clinical Diagnostics Vitros. We examined 123 patient specimens. In the first phase of the study, we compared 99 specimens that had a positive screening result via the 3rd-generation Vitros assay (10 positive, 82 negative, and 7 indeterminate via confirmatory immunofluorescent assay [IFA]/Western blot [WB] testing). In the second phase, we assessed 24 HIV-1 RNA-positive (positive result via the nuclear acid amplification test [NAAT] and negative/indeterminate results via the WB test) specimens harboring acute HIV infection. The 4th-generation ARCHITECT assay yielded fewer false-positive results (n = 2) than the 3rd-generation Centaur (n = 9; P = .02) and Vitros (n = 82; P <.001) assays. One confirmed positive case had a false-negative result via the Centaur assay. When specimens from the 24 patients with acute HIV-1 infection were tested, the ARCHITECT assay yielded fewer false-negative results (n = 5) than the Centaur (n = 10) (P = .13) and the other 3rd-generation tests (n = 16) (P = .002). This study indicates that the 4th-generation ARCHITECT HIV assay yields fewer false-positive and false-negative results than the 3rd-generation HIV assays we tested. Copyright© by the American Society for Clinical Pathology (ASCP).
Minimum Bayes risk image correlation

NASA Technical Reports Server (NTRS)

Minter, T. C., Jr.

1980-01-01

In this paper, the problem of designing a matched filter for image correlation will be treated as a statistical pattern recognition problem. It is shown that, by minimizing a suitable criterion, a matched filter can be estimated which approximates the optimum Bayes discriminant function in a least-squares sense. It is well known that the use of the Bayes discriminant function in target classification minimizes the Bayes risk, which in turn directly minimizes the probability of a false fix. A fast Fourier implementation of the minimum Bayes risk correlation procedure is described.
Minimal measures on surfaces of higher genus

NASA Astrophysics Data System (ADS)

Wang, Fang

We study the minimal measures for positive definite autonomous Lagrangian systems defined on the tangent bundles of compact surfaces with genus greater than one. We present some results on the structure of minimal measures on compact surfaces. Specifically, we give a finer description of the structure of minimal measures with rational rotation vectors for geodesic flows on compact surfaces.
Revisiting venom of the sea anemone Stichodactyla haddoni: Omics techniques reveal the complete toxin arsenal of a well-studied sea anemone genus.

PubMed

Madio, Bruno; Undheim, Eivind A B; King, Glenn F

2017-08-23

More than a century of research on sea anemone venoms has shown that they contain a diversity of biologically active proteins and peptides. However, recent omics studies have revealed that much of the venom proteome remains unexplored. We used, for the first time, a combination of proteomic and transcriptomic techniques to obtain a holistic overview of the venom arsenal of the well-studied sea anemone Stichodactyla haddoni. A purely search-based approach to identify putative toxins in a transcriptome from tentacles regenerating after venom extraction identified 508 unique toxin-like transcripts grouped into 63 families. However, proteomic analysis of venom revealed that 52 of these toxin families are likely false positives. In contrast, the combination of transcriptomic and proteomic data enabled positive identification of 23 families of putative toxins, 12 of which have no homology known proteins or peptides. Our data highlight the importance of using proteomics of milked venom to correctly identify venom proteins/peptides, both known and novel, while minimizing false positive identifications from non-toxin homologues identified in transcriptomes of venom-producing tissues. This work lays the foundation for uncovering the role of individual toxins in sea anemone venom and how they contribute to the envenomation of prey, predators, and competitors. Proteomic analysis of milked venom combined with analysis of a tentacle transcriptome revealed the full extent of the venom arsenal of the sea anemone Stichodactyla haddoni. This combined approach led to the discovery of 12 entirely new families of disulfide-rich peptides and proteins in a genus of anemones that have been studied for over a century. Copyright © 2017 Elsevier B.V. All rights reserved.
Is there a positive bias in false recognition? Evidence from confabulating amnesia patients.

PubMed

Alkathiri, Nura H; Morris, Robin G; Kopelman, Michael D

2015-10-01

Although there is some evidence for a positive emotional bias in the content of confabulations in brain damaged patients, findings have been inconsistent. The present study used the semantic-associates procedure to induce false recall and false recognition in order to examine whether a positive bias would be found in confabulating amnesic patients, relative to non-confabulating amnesic patients and healthy controls. Lists of positive, negative and neutral words were presented in order to induce false recall or false recognition of non-presented (but semantically associated) words. The latter were termed 'critical intrusions'. Thirteen confabulating amnesic patients, 13 non-confabulating amnesic patients and 13 healthy controls were investigated. Confabulating patients falsely recognised a higher proportion of positive (but unrelated) words, compared with non-confabulating patients and healthy controls. No differences were found for recall memory. Signal detection analysis, however, indicated that the positive bias for false recognition memory might reflect weaker memory in the confabulating amnesic group. This suggested that amnesia patients with weaker memory are more likely to confabulate and the content of these confabulations are more likely to be positive. Copyright © 2015 Elsevier Ltd. All rights reserved.
Study of false positives in 5-ALA induced photodynamic diagnosis of bladder carcinoma

NASA Astrophysics Data System (ADS)

Draga, Ronald O. P.; Grimbergen, Matthijs C. M.; Kok, Esther T.; Jonges, Trudy G. N.; Bosch, J. L. H. R.

2009-02-01

Photodynamic diagnosis (PDD) is a technique that enhances the detection of tumors during cystoscopy using a photosensitizer which accumulates primarily in cancerous cells and will fluoresce when illuminated by violetblue light. A disadvantage of PDD is the relatively low specificity. In this retrospective study we aimed to identify predictors for false positive findings in PDD. Factors such as gender, age, recent transurethral resection of bladder tumors (TURBT), previous intravesical therapy (IVT) and urinary tract infections (UTIs) were examined for association with the false positive rates in a multivariate analysis. Data of 366 procedures and 200 patients were collected. Patients were instilled with 5-aminolevulinic acid (5-ALA) intravesically and 1253 biopsies were taken from tumors and suspicious lesions. Female gender and TURBT are independent predictors of false positives in PDD. However, previous intravesical therapy with Bacille Calmette-Guérin is also an important predictor of false positives. The false positive rate decreases during the first 9-12 weeks after the latest TURBT and the latest intravesical chemotherapy. Although shortly after IVT and TURBT false positives increase, PDD improves the diagnostic sensitivity and results in more adequate treatment strategies in a significant number of patients.
The health system impact of false positive newborn screening results for medium-chain acyl-CoA dehydrogenase deficiency: a cohort study.

PubMed

Karaceper, Maria D; Chakraborty, Pranesh; Coyle, Doug; Wilson, Kumanan; Kronick, Jonathan B; Hawken, Steven; Davies, Christine; Brownell, Marni; Dodds, Linda; Feigenbaum, Annette; Fell, Deshayne B; Grosse, Scott D; Guttmann, Astrid; Laberge, Anne-Marie; Mhanni, Aizeddin; Miller, Fiona A; Mitchell, John J; Nakhla, Meranda; Prasad, Chitra; Rockman-Greenberg, Cheryl; Sparkes, Rebecca; Wilson, Brenda J; Potter, Beth K

2016-02-03

There is no consensus in the literature regarding the impact of false positive newborn screening results on early health care utilization patterns. We evaluated the impact of false positive newborn screening results for medium-chain acyl-CoA dehydrogenase deficiency (MCADD) in a cohort of Ontario infants. The cohort included all children who received newborn screening in Ontario between April 1, 2006 and March 31, 2010. Newborn screening and diagnostic confirmation results were linked to province-wide health care administrative datasets covering physician visits, emergency department visits, and inpatient hospitalizations, to determine health service utilization from April 1, 2006 through March 31, 2012. Incidence rate ratios (IRRs) were used to compare those with false positive results for MCADD to those with negative newborn screening results, stratified by age at service use. We identified 43 infants with a false positive newborn screening result for MCADD during the study period. These infants experienced significantly higher rates of physician visits (IRR: 1.42) and hospitalizations (IRR: 2.32) in the first year of life relative to a screen negative cohort in adjusted analyses. Differences in health services use were not observed after the first year of life. The higher use of some health services among false positive infants during the first year of life may be explained by a psychosocial impact of false positive results on parental perceptions of infant health, and/or by differences in underlying health status. Understanding the impact of false positive newborn screening results can help to inform newborn screening programs in designing support and education for families. This is particularly important as additional disorders are added to expanded screening panels, yielding important clinical benefits for affected children but also a higher frequency of false positive findings.
Accounting for false-positive acoustic detections of bats using occupancy models

USGS Publications Warehouse

Clement, Matthew J.; Rodhouse, Thomas J.; Ormsbee, Patricia C.; Szewczak, Joseph M.; Nichols, James D.

2014-01-01

4. Synthesis and applications. Our results suggest that false positives sufficient to affect inferences may be common in acoustic surveys for bats. We demonstrate an approach that can estimate occupancy, regardless of the false-positive rate, when acoustic surveys are paired with capture surveys. Applications of this approach include monitoring the spread of White-Nose Syndrome, estimating the impact of climate change and informing conservation listing decisions. We calculate a site-specific probability of occupancy, conditional on survey results, which could inform local permitting decisions, such as for wind energy projects. More generally, the magnitude of false positives suggests that false-positive occupancy models can improve accuracy in research and monitoring of bats and provide wildlife managers with more reliable information.
Significance chasing in research practice: causes, consequences and possible solutions.

PubMed

Ware, Jennifer J; Munafò, Marcus R

2015-01-01

The low reproducibility of findings within the scientific literature is a growing concern. This may be due to many findings being false positives which, in turn, can misdirect research effort and waste money. We review factors that may contribute to poor study reproducibility and an excess of 'significant' findings within the published literature. Specifically, we consider the influence of current incentive structures and the impact of these on research practices. The prevalence of false positives within the literature may be attributable to a number of questionable research practices, ranging from the relatively innocent and minor (e.g. unplanned post-hoc tests) to the calculated and serious (e.g. fabrication of data). These practices may be driven by current incentive structures (e.g. pressure to publish), alongside the preferential emphasis placed by journals on novelty over veracity. There are a number of potential solutions to poor reproducibility, such as new publishing formats that emphasize the research question and study design, rather than the results obtained. This has the potential to minimize significance chasing and non-publication of null findings. Significance chasing, questionable research practices and poor study reproducibility are the unfortunate consequence of a 'publish or perish' culture and a preference among journals for novel findings. It is likely that top-down change implemented by those with the ability to modify current incentive structure (e.g. funders and journals) will be required to address problems of poor reproducibility. © 2014 Society for the Study of Addiction.
PHYCAA+: an optimized, adaptive procedure for measuring and controlling physiological noise in BOLD fMRI.

PubMed

Churchill, Nathan W; Strother, Stephen C

2013-11-15

The presence of physiological noise in functional MRI can greatly limit the sensitivity and accuracy of BOLD signal measurements, and produce significant false positives. There are two main types of physiological confounds: (1) high-variance signal in non-neuronal tissues of the brain including vascular tracts, sinuses and ventricles, and (2) physiological noise components which extend into gray matter tissue. These physiological effects may also be partially coupled with stimuli (and thus the BOLD response). To address these issues, we have developed PHYCAA+, a significantly improved version of the PHYCAA algorithm (Churchill et al., 2011) that (1) down-weights the variance of voxels in probable non-neuronal tissue, and (2) identifies the multivariate physiological noise subspace in gray matter that is linked to non-neuronal tissue. This model estimates physiological noise directly from EPI data, without requiring external measures of heartbeat and respiration, or manual selection of physiological components. The PHYCAA+ model significantly improves the prediction accuracy and reproducibility of single-subject analyses, compared to PHYCAA and a number of commonly-used physiological correction algorithms. Individual subject denoising with PHYCAA+ is independently validated by showing that it consistently increased between-subject activation overlap, and minimized false-positive signal in non gray-matter loci. The results are demonstrated for both block and fast single-event task designs, applied to standard univariate and adaptive multivariate analysis models. Copyright © 2013 Elsevier Inc. All rights reserved.
Linker-assisted immunoassay and liquid chromatography/mass spectrometry for the analysis of glyphosate

USGS Publications Warehouse

Lee, E.A.; Zimmerman, L.R.; Bhullar, B.S.; Thurman, E.M.

2002-01-01

A novel, sensitive, linker-assisted enzyme-linked immunosorbent assay (L'ELISA) was compared to on-line solidphase extraction (SPE) with high-performance liquid chromatography/mass spectrometry (HPLC/MS) for the analysis of glyphosate in surface water and groundwater samples. The L'ELISA used succinic anhydride to derivatize glyphosate, which mimics the epitotic attachment of glyphosate to horseradish peroxidase hapten. Thus, L'ELISA recognized the derivatized glyphosate more effectively (detection limit of 0.1 μg/L) and with increased sensitivity (10-100 times) over conventional ELISA and showed the potential for other applications. The precision and accuracy of L'ELISA then was compared with on-line SPE/HPLC/MS, which detected glyphosate and its degradate derivatized with 9-fluorenylmethyl chloroformate using negative-ion electrospray (detection limit 0.1 μg/L, relative standard deviation ±15%). Derivatization efficiency and matrix effects were minimized by adding an isotope-labeled glyphosate (2-13C15N). The accuracy of L'ELISA gave a false positive rate of 18% between 0.1 and 1.0 μg/L and a false positive rate of only 1% above 1.0 μg/L. The relative standard deviation was ±20%. The correlation of L'ELISA and HPLC/MS for 66 surface water and groundwater samples was 0.97 with a slope of 1.28, with many detections of glyphosate and its degradate in surface water but not in groundwater.
Detecting outliers when fitting data with nonlinear regression – a new method based on robust nonlinear regression and the false discovery rate

PubMed Central

Motulsky, Harvey J; Brown, Ronald E

2006-01-01

Background Nonlinear regression, like linear regression, assumes that the scatter of data around the ideal curve follows a Gaussian or normal distribution. This assumption leads to the familiar goal of regression: to minimize the sum of the squares of the vertical or Y-value distances between the points and the curve. Outliers can dominate the sum-of-the-squares calculation, and lead to misleading results. However, we know of no practical method for routinely identifying outliers when fitting curves with nonlinear regression. Results We describe a new method for identifying outliers when fitting data with nonlinear regression. We first fit the data using a robust form of nonlinear regression, based on the assumption that scatter follows a Lorentzian distribution. We devised a new adaptive method that gradually becomes more robust as the method proceeds. To define outliers, we adapted the false discovery rate approach to handling multiple comparisons. We then remove the outliers, and analyze the data using ordinary least-squares regression. Because the method combines robust regression and outlier removal, we call it the ROUT method. When analyzing simulated data, where all scatter is Gaussian, our method detects (falsely) one or more outlier in only about 1–3% of experiments. When analyzing data contaminated with one or several outliers, the ROUT method performs well at outlier identification, with an average False Discovery Rate less than 1%. Conclusion Our method, which combines a new method of robust nonlinear regression with a new method of outlier identification, identifies outliers from nonlinear curve fits with reasonable power and few false positives. PMID:16526949
Analysis of false results in a series of 835 fine needle aspirates of breast lesions.

PubMed

Willis, S L; Ramzy, I

1995-01-01

To analyze cases of false diagnoses from a large series to help increase the accuracy of fine needle aspiration of palpable breast lesions. The results of FNA of 835 palpable breast lesions were analyzed to determine the reasons for false positive, false negative and false suspicious diagnoses. Of the 835 aspirates, 174 were reported as positive, 549 as negative and 66 as suspicious or atypical but not diagnostic of malignancy. Forty-six cases were considered unsatisfactory. Tissue was available for comparison in 286 cases. The cytologic diagnoses in these cases were reported as follows: positive, 125 (43.7%); suspicious, 33 (11.5%); atypical, 18 (6.2%); negative, 92 (32%); and unsatisfactory, 18 (6.2%). There was one false positive diagnosis, yielding a false positive rate of 0.8%. This lesion was a case of fibrocystic change with hyperplasia, focal fat necrosis and reparative atypia. There were 14 false negative cases, resulting in a false negative rate of 13.2%. Nearly all these cases were sampling errors and included infiltrating ductal carcinomas (9), ductal carcinomas in situ (2), infiltrating lobular carcinomas (2) and tubular carcinoma (1). Most of the suspicious and atypical lesions proved to be carcinomas (35/50). The remainder were fibroadenomas (6), fibrocystic change (4), gynecomastia (2), adenosis (2) and granulomatous mastitis (1). A positive diagnosis of malignancy by FNA is reliable in establishing the diagnosis and planning the treatment of breast cancer. The false-positive rate is very low, with only a single case reported in 835 aspirates. Most false negatives are due to sampling and not to interpretive difficulties. The category "suspicious but not diagnostic of malignancy" serves a useful purpose in management of patients with breast lumps.

Uncertainty in biological monitoring: a framework for data collection and analysis to account for multiple sources of sampling bias

USGS Publications Warehouse

Ruiz-Gutierrez, Viviana; Hooten, Melvin B.; Campbell Grant, Evan H.

2016-01-01

Biological monitoring programmes are increasingly relying upon large volumes of citizen-science data to improve the scope and spatial coverage of information, challenging the scientific community to develop design and model-based approaches to improve inference.Recent statistical models in ecology have been developed to accommodate false-negative errors, although current work points to false-positive errors as equally important sources of bias. This is of particular concern for the success of any monitoring programme given that rates as small as 3% could lead to the overestimation of the occurrence of rare events by as much as 50%, and even small false-positive rates can severely bias estimates of occurrence dynamics.We present an integrated, computationally efficient Bayesian hierarchical model to correct for false-positive and false-negative errors in detection/non-detection data. Our model combines independent, auxiliary data sources with field observations to improve the estimation of false-positive rates, when a subset of field observations cannot be validated a posteriori or assumed as perfect. We evaluated the performance of the model across a range of occurrence rates, false-positive and false-negative errors, and quantity of auxiliary data.The model performed well under all simulated scenarios, and we were able to identify critical auxiliary data characteristics which resulted in improved inference. We applied our false-positive model to a large-scale, citizen-science monitoring programme for anurans in the north-eastern United States, using auxiliary data from an experiment designed to estimate false-positive error rates. Not correcting for false-positive rates resulted in biased estimates of occupancy in 4 of the 10 anuran species we analysed, leading to an overestimation of the average number of occupied survey routes by as much as 70%.The framework we present for data collection and analysis is able to efficiently provide reliable inference for occurrence patterns using data from a citizen-science monitoring programme. However, our approach is applicable to data generated by any type of research and monitoring programme, independent of skill level or scale, when effort is placed on obtaining auxiliary information on false-positive rates.
[Predictive factors of contamination in a blood culture with bacterial growth in an Emergency Department].

PubMed

Hernández-Bou, S; Trenchs Sainz de la Maza, V; Esquivel Ojeda, J N; Gené Giralt, A; Luaces Cubells, C

2015-06-01

The aim of this study is to identify predictive factors of bacterial contamination in positive blood cultures (BC) collected in an emergency department. A prospective, observational and analytical study was conducted on febrile children aged on to 36 months, who had no risk factors of bacterial infection, and had a BC collected in the Emergency Department between November 2011 and October 2013 in which bacterial growth was detected. The potential BC contamination predicting factors analysed were: maximum temperature, time to positivity, initial Gram stain result, white blood cell count, absolute neutrophil count, band count, and C-reactive protein (CRP). Bacteria grew in 169 BC. Thirty (17.8%) were finally considered true positives and 139 (82.2%) false positives. All potential BC contamination predicting factors analysed, except maximum temperature, showed significant differences between true positives and false positives. CRP value, time to positivity, and initial Gram stain result are the best predictors of false positives in BC. The positive predictive values of a CRP value≤30mg/L, BC time to positivity≥16h, and initial Gram stain suggestive of a contaminant in predicting a FP, are 95.1, 96.9 and 97.5%, respectively. When all 3 conditions are applied, their positive predictive value is 100%. Four (8.3%) patients with a false positive BC and discharged to home were revaluated in the Emergency Department. The majority of BC obtained in the Emergency Department that showed positive were finally considered false positives. Initial Gram stain, time to positivity, and CRP results are valuable diagnostic tests in distinguishing between true positives and false positives in BC. The early detection of false positives will allow minimising their negative consequences. Copyright © 2014 Asociación Española de Pediatría. Published by Elsevier España, S.L.U. All rights reserved.
Interpreting the results of the Semmes-Weinstein monofilament test: accounting for false-positive answers in the international consensus on the diabetic foot protocol by a new model.

PubMed

Slater, Robert A; Koren, Shlomit; Ramot, Yoram; Buchs, Andreas; Rapoport, Micha J

2014-01-01

The Semmes-Weinstein monofilament is the most widely used test to diagnose the loss of protective sensation. The commonly used protocol of the International Consensus on the Diabetic Foot includes a 'sham' application that allows for false-positive answers. We sought to study the heretofore unexamined significance of false-positive answers. Forty-five patients with diabetes and a history of pedal ulceration (Group I) and 81 patients with diabetes but no history of ulceration (Group II) were studied. The three original sites of the International Consensus on the Diabetic Foot at the hallux, 1st metatarsal and 5th metatarsal areas were used. At each location, the test was performed three times: 2 actual and 1 "sham" applications. Scores were graded from 0 to 3 based upon correct responses. Determination of loss of protective sensation was performed with and without calculating a false-positive answer as a minus 1 score. False-positive responses were found in a significant percentage of patients with and without history of ulceration. Introducing false-positive results as minus 1 into the test outcome significantly increased the number of patients diagnosed with loss of protective sensation in both groups. False-positive answers can significantly affect Semmes-Weinstein monofilament test results and the diagnosis of LOPS. A model that accounts for false-positive answers is offered. Copyright © 2013 John Wiley & Sons, Ltd.
Compact and highly active next-generation libraries for CRISPR-mediated gene repression and activation

PubMed Central

Horlbeck, Max A; Gilbert, Luke A; Villalta, Jacqueline E; Adamson, Britt; Pak, Ryan A; Chen, Yuwen; Fields, Alexander P; Park, Chong Yon; Corn, Jacob E; Kampmann, Martin; Weissman, Jonathan S

2016-01-01

We recently found that nucleosomes directly block access of CRISPR/Cas9 to DNA (Horlbeck et al., 2016). Here, we build on this observation with a comprehensive algorithm that incorporates chromatin, position, and sequence features to accurately predict highly effective single guide RNAs (sgRNAs) for targeting nuclease-dead Cas9-mediated transcriptional repression (CRISPRi) and activation (CRISPRa). We use this algorithm to design next-generation genome-scale CRISPRi and CRISPRa libraries targeting human and mouse genomes. A CRISPRi screen for essential genes in K562 cells demonstrates that the large majority of sgRNAs are highly active. We also find CRISPRi does not exhibit any detectable non-specific toxicity recently observed with CRISPR nuclease approaches. Precision-recall analysis shows that we detect over 90% of essential genes with minimal false positives using a compact 5 sgRNA/gene library. Our results establish CRISPRi and CRISPRa as premier tools for loss- or gain-of-function studies and provide a general strategy for identifying Cas9 target sites. DOI: http://dx.doi.org/10.7554/eLife.19760.001 PMID:27661255
How do we assign punishment? The impact of minimal and maximal standards on the evaluation of deviants.

PubMed

Kessler, Thomas; Neumann, Jörg; Mummendey, Amélie; Berthold, Anne; Schubert, Thomas; Waldzus, Sven

2010-09-01

To explain the determinants of negative behavior toward deviants (e.g., punishment), this article examines how people evaluate others on the basis of two types of standards: minimal and maximal. Minimal standards focus on an absolute cutoff point for appropriate behavior; accordingly, the evaluation of others varies dichotomously between acceptable or unacceptable. Maximal standards focus on the degree of deviation from that standard; accordingly, the evaluation of others varies gradually from positive to less positive. This framework leads to the prediction that violation of minimal standards should elicit punishment regardless of the degree of deviation, whereas punishment in response to violations of maximal standards should depend on the degree of deviation. Four studies assessed or manipulated the type of standard and degree of deviation displayed by a target. Results consistently showed the expected interaction between type of standard (minimal and maximal) and degree of deviation on punishment behavior.
The utility of a handheld metal detector in detection and localization of pediatric metallic foreign body ingestion.

PubMed

Nation, Javan; Jiang, Wen

2017-01-01

To test the ability of a handheld metal detector (HHMD) to identify the presence and location of ingested metallic foreign bodies (MFBs) in children. Prospective case series enrolling children suspected of metallic foreign body ingestion presenting to the Emergency Department. Thirty-eight children were enrolled and the HHMD was used to detect the presence and location of a MFB. Results were compared to standard radiographic studies. Thirty-seven of the 38 ingested foreign bodies were MFBs. Of the 37 MFBs, the HHMD positively identified 33, and 4 were missed by HHMD but identified on radiography. When positive, the location indicated by HHMD correlated 100% with radiograph. There were 33 true positives, 0 false positives, 4 false negatives, and 1 true negative. This resulted in a sensitivity of 89% (95% CI of 75%-96%) and specificity of 100% (95% CI of 2.5%-100%). Our study demonstrates the accuracy of HHMD in the identification and localization of metallic foreign bodies. We propose an emergency room foreign body protocol that uses HHMD as an early screening tool in triage in order to expedite the process of obtaining Otolaryngology consultation and potentially shorten the wait time to the operating room or discharge. In instances were outside films are previously performed, HHMD use may be able to minimize the overall radiation exposure to children by obviating the need for repeat radiographs. As the sensitivity is not 100%, a negative HHMD screening does not negate the need for a standard radiograph in order to avoid missed MFBs. HHMD is best suited for detection of coins, which accounts for the majority of the MFB ingestions, and may not be suitable for all metallic objects since the amount of metal may decrease its sensitivity. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.
Tile-based Fisher ratio analysis of comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry (GC × GC-TOFMS) data using a null distribution approach.

PubMed

Parsons, Brendon A; Marney, Luke C; Siegler, W Christopher; Hoggard, Jamin C; Wright, Bob W; Synovec, Robert E

2015-04-07

Comprehensive two-dimensional (2D) gas chromatography coupled with time-of-flight mass spectrometry (GC × GC-TOFMS) is a versatile instrumental platform capable of collecting highly informative, yet highly complex, chemical data for a variety of samples. Fisher-ratio (F-ratio) analysis applied to the supervised comparison of sample classes algorithmically reduces complex GC × GC-TOFMS data sets to find class distinguishing chemical features. F-ratio analysis, using a tile-based algorithm, significantly reduces the adverse effects of chromatographic misalignment and spurious covariance of the detected signal, enhancing the discovery of true positives while simultaneously reducing the likelihood of detecting false positives. Herein, we report a study using tile-based F-ratio analysis whereby four non-native analytes were spiked into diesel fuel at several concentrations ranging from 0 to 100 ppm. Spike level comparisons were performed in two regimes: comparing the spiked samples to the nonspiked fuel matrix and to each other at relative concentration factors of two. Redundant hits were algorithmically removed by refocusing the tiled results onto the original high resolution pixel level data. To objectively limit the tile-based F-ratio results to only features which are statistically likely to be true positives, we developed a combinatorial technique using null class comparisons, called null distribution analysis, by which we determined a statistically defensible F-ratio cutoff for the analysis of the hit list. After applying null distribution analysis, spiked analytes were reliably discovered at ∼1 to ∼10 ppm (∼5 to ∼50 pg using a 200:1 split), depending upon the degree of mass spectral selectivity and 2D chromatographic resolution, with minimal occurrence of false positives. To place the relevance of this work among other methods in this field, results are compared to those for pixel and peak table-based approaches.
The problem of false positives and false negatives in violent video game experiments.

PubMed

Ferguson, Christopher J

The problem of false positives and negatives has received considerable attention in behavioral research in recent years. The current paper uses video game violence research as an example of how such issues may develop in a field. Despite decades of research, evidence on whether violent video games (VVGs) contribute to aggression in players has remained mixed. Concerns have been raised in recent years that experiments regarding VVGs may suffer from both "false positives" and "false negatives." The current paper examines this issue in three sets of video game experiments, two sets of video game experiments on aggression and prosocial behaviors identified in meta-analysis, and a third group of recent null studies. Results indicated that studies of VVGs and aggression appear to be particularly prone to false positive results. Studies of VVGs and prosocial behavior, by contrast are heterogeneous and did not demonstrate any indication of false positive results. However, their heterogeneous nature made it difficult to base solid conclusions on them. By contrast, evidence for false negatives in null studies was limited, and little evidence emerged that null studies lacked power in comparison those highlighted in past meta-analyses as evidence for effects. These results are considered in light of issues related to false positives and negatives in behavioral science more broadly. Copyright © 2017 Elsevier Ltd. All rights reserved.
Analysis of S-nitrosothiols via Copper Cysteine (2C) and Copper Cysteine - Carbon Monoxide (3C) Methods

PubMed Central

Rogers, Stephen C.; Gibbons, Lindsey B.; Griffin, Sherraine; Doctor, Allan

2012-01-01

This chapter summarizes the principles of RSNO measurement in the gas phase, utilizing ozone-based chemiluminescence and the copper cysteine (2C) ± carbon monoxide (3C) reagent. Although an indirect method for quantifying RSNOs, this assay represents one of the most robust methodologies available. It exploits the NO• detection sensitivity of ozone based chemiluminscence, which is within the range required to detect physiological concentrations of RSNO metabolites. Additionally, the specificity of the copper cysteine (2C and 3C) reagent for RSNOs negates the need for sample pretreatment, thereby minimizing the likelihood of sample contamination (false positive results), NO species inter-conversion, or the loss of certain highly labile RSNO species. Herein, we outline the principles of this methodology, summarizing key issues, potential pitfalls and corresponding solutions. PMID:23116707
Corrigendum: New Form of Kane's Equations of Motion for Constrained Systems

NASA Technical Reports Server (NTRS)

Roithmayr, Carlos M.; Bajodah, Abdulrahman H.; Hodges, Dewey H.; Chen, Ye-Hwa

2007-01-01

A correction to the previously published article "New Form of Kane's Equations of Motion for Constrained Systems" is presented. Misuse of the transformation matrix between time rates of change of the generalized coordinates and generalized speeds (sometimes called motion variables) resulted in a false conclusion concerning the symmetry of the generalized inertia matrix. The generalized inertia matrix (sometimes referred to as the mass matrix) is in fact symmetric and usually positive definite when one forms nonminimal Kane's equations for holonomic or simple nonholonomic systems, systems subject to nonlinear nonholonomic constraints, and holonomic or simple nonholonomic systems subject to impulsive constraints according to Refs. 1, 2, and 3, respectively. The mass matrix is of course symmetric when one forms minimal equations for holonomic or simple nonholonomic systems using Kane s method as set forth in Ref. 4.
Accounting for False Positive HIV Tests: Is Visceral Leishmaniasis Responsible?

PubMed Central

Shanks, Leslie; Ritmeijer, Koert; Piriou, Erwan; Siddiqui, M. Ruby; Kliescikova, Jarmila; Pearce, Neil; Ariti, Cono; Muluneh, Libsework; Masiga, Johnson; Abebe, Almaz

2015-01-01

Background Co-infection with HIV and visceral leishmaniasis is an important consideration in treatment of either disease in endemic areas. Diagnosis of HIV in resource-limited settings relies on rapid diagnostic tests used together in an algorithm. A limitation of the HIV diagnostic algorithm is that it is vulnerable to falsely positive reactions due to cross reactivity. It has been postulated that visceral leishmaniasis (VL) infection can increase this risk of false positive HIV results. This cross sectional study compared the risk of false positive HIV results in VL patients with non-VL individuals. Methodology/Principal Findings Participants were recruited from 2 sites in Ethiopia. The Ethiopian algorithm of a tiebreaker using 3 rapid diagnostic tests (RDTs) was used to test for HIV. The gold standard test was the Western Blot, with indeterminate results resolved by PCR testing. Every RDT screen positive individual was included for testing with the gold standard along with 10% of all negatives. The final analysis included 89 VL and 405 non-VL patients. HIV prevalence was found to be 12.8% (47/ 367) in the VL group compared to 7.9% (200/2526) in the non-VL group. The RDT algorithm in the VL group yielded 47 positives, 4 false positives, and 38 negatives. The same algorithm for those without VL had 200 positives, 14 false positives, and 191 negatives. Specificity and positive predictive value for the group with VL was less than the non-VL group; however, the difference was not found to be significant (p = 0.52 and p = 0.76, respectively). Conclusion The test algorithm yielded a high number of HIV false positive results. However, we were unable to demonstrate a significant difference between groups with and without VL disease. This suggests that the presence of endemic visceral leishmaniasis alone cannot account for the high number of false positive HIV results in our study. PMID:26161864
Accounting for False Positive HIV Tests: Is Visceral Leishmaniasis Responsible?

PubMed

Shanks, Leslie; Ritmeijer, Koert; Piriou, Erwan; Siddiqui, M Ruby; Kliescikova, Jarmila; Pearce, Neil; Ariti, Cono; Muluneh, Libsework; Masiga, Johnson; Abebe, Almaz

2015-01-01

Co-infection with HIV and visceral leishmaniasis is an important consideration in treatment of either disease in endemic areas. Diagnosis of HIV in resource-limited settings relies on rapid diagnostic tests used together in an algorithm. A limitation of the HIV diagnostic algorithm is that it is vulnerable to falsely positive reactions due to cross reactivity. It has been postulated that visceral leishmaniasis (VL) infection can increase this risk of false positive HIV results. This cross sectional study compared the risk of false positive HIV results in VL patients with non-VL individuals. Participants were recruited from 2 sites in Ethiopia. The Ethiopian algorithm of a tiebreaker using 3 rapid diagnostic tests (RDTs) was used to test for HIV. The gold standard test was the Western Blot, with indeterminate results resolved by PCR testing. Every RDT screen positive individual was included for testing with the gold standard along with 10% of all negatives. The final analysis included 89 VL and 405 non-VL patients. HIV prevalence was found to be 12.8% (47/ 367) in the VL group compared to 7.9% (200/2526) in the non-VL group. The RDT algorithm in the VL group yielded 47 positives, 4 false positives, and 38 negatives. The same algorithm for those without VL had 200 positives, 14 false positives, and 191 negatives. Specificity and positive predictive value for the group with VL was less than the non-VL group; however, the difference was not found to be significant (p = 0.52 and p = 0.76, respectively). The test algorithm yielded a high number of HIV false positive results. However, we were unable to demonstrate a significant difference between groups with and without VL disease. This suggests that the presence of endemic visceral leishmaniasis alone cannot account for the high number of false positive HIV results in our study.
Relevance of cutoff on a 4th generation ELISA performance in the false positive rate during HIV diagnostic in a low HIV prevalence setting.

PubMed

Chacón, Lucía; Mateos, María Luisa; Holguín, África

2017-07-01

Despite the high specificity of fourth-generation enzyme immunoassays (4th-gen-EIA) for screening during HIV diagnosis, their positive predictive value is low in populations with low HIV prevalence. Thus, screening should be optimized to reduce false positive results. The influence of sample cutoff (S/CO) values by a 4th-gen-EIA with the false positive rate during the routine HIV diagnosis in a low HIV prevalence population was evaluated. A total of 30,201 sera were tested for HIV diagnosis using Abbott Architect ® HIV-Ag/Ab-Combo 4th-gen-EIA at a hospital in Spain during 17 months. Architect S/CO values were recorded, comparing the HIV-1 positive results following Architect interpretation (S/CO≥1) with the final HIV-1 diagnosis by confirmatory tests (line immunoassay, LIA and/or nucleic acid test, NAT). ROC curve was also performed. Among the 30,201 HIV performed tests, 256 (0.85%) were positive according to Architect interpretation (S/CO≥1) but only 229 (0.76%) were definitively HIV-1 positive after LIA and/or NAT. Thus, 27 (10.5%) of 256 samples with S/CO≥1 by Architect were false positive diagnose. The false positive rate decreased when the S/CO ratio increased. All 19 samples with S/CO ≤10 were false positives and all 220 with S/CO>50 true HIV-positives. The optimal S/CO cutoff value provided by ROC curves was 32.7. No false negative results were found. We show that very low S/CO values during HIV-1 screening using Architect can result HIV negative after confirmation by LIA and NAT. The false positive rate is reduced when S/CO increases. Copyright © 2017 Elsevier B.V. All rights reserved.
Which Factors Contribute to False-Positive, False-Negative, and Invalid Results in Fetal Fibronectin Testing in Women with Symptoms of Preterm Labor?

PubMed

Bruijn, Merel M C; Hermans, Frederik J R; Vis, Jolande Y; Wilms, Femke F; Oudijk, Martijn A; Kwee, Anneke; Porath, Martina M; Oei, Guid; Scheepers, Hubertina C J; Spaanderman, Marc E A; Bloemenkamp, Kitty W M; Haak, Monique C; Bolte, Antoinette C; Vandenbussche, Frank P H A; Woiski, Mallory D; Bax, Caroline J; Cornette, Jérôme M J; Duvekot, Johannes J; Bijvank, Bas W A N I J; van Eyck, Jim; Franssen, Maureen T M; Sollie, Krystyna M; van der Post, Joris A M; Bossuyt, Patrick M M; Kok, Marjolein; Mol, Ben W J; van Baaren, Gert-Jan

2017-02-01

Objective We assessed the influence of external factors on false-positive, false-negative, and invalid fibronectin results in the prediction of spontaneous delivery within 7 days. Methods We studied symptomatic women between 24 and 34 weeks' gestational age. We performed uni- and multivariable logistic regression to estimate the effect of external factors (vaginal soap, digital examination, transvaginal sonography, sexual intercourse, vaginal bleeding) on the risk of false-positive, false-negative, and invalid results, using spontaneous delivery within 7 days as the outcome. Results Out of 708 women, 237 (33%) had a false-positive result; none of the factors showed a significant association. Vaginal bleeding increased the proportion of positive fetal fibronectin (fFN) results, but was significantly associated with a lower risk of false-positive test results (odds ratio [OR], 0.22; 95% confidence intervals [CI], 0.12-0.39). Ten women (1%) had a false-negative result. None of the investigated factors was significantly associated with a significantly higher risk of false-negative results. Twenty-one tests (3%) were invalid; only vaginal bleeding showed a significant association (OR, 4.5; 95% CI, 1.7-12). Conclusion The effect of external factors on the performance of qualitative fFN testing is limited, with vaginal bleeding as the only factor that reduces its validity. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.
Consensus-based identification of factors related to false-positives in ultrasound scanning of synovitis and tenosynovitis.

PubMed

Ikeda, Kei; Narita, Akihiro; Ogasawara, Michihiro; Ohno, Shigeru; Kawahito, Yutaka; Kawakami, Atsushi; Ito, Hiromu; Matsushita, Isao; Suzuki, Takeshi; Misaki, Kenta; Ogura, Takehisa; Kamishima, Tamotsu; Seto, Yohei; Nakahara, Ryuichi; Kaneko, Atsushi; Nakamura, Takayuki; Henmi, Mihoko; Fukae, Jun; Nishida, Keiichiro; Sumida, Takayuki; Koike, Takao

2016-01-01

We aimed to identify causes of false-positives in ultrasound scanning of synovial/tenosynovial/bursal inflammation and provide corresponding imaging examples. We first performed systematic literature review to identify previously reported causes of false-positives. We next determined causes of false-positives and corresponding example images for educational material through Delphi exercises and discussion by 15 experts who were an instructor and/or a lecturer in the 2013 advanced course for musculoskeletal ultrasound organized by Japan College of Rheumatology Committee for the Standardization of Musculoskeletal Ultrasonography. Systematic literature review identified 11 articles relevant to sonographic false-positives of synovial/tenosynovial inflammation. Based on these studies, 21 candidate causes of false-positives were identified in the consensus meeting. Of these items, 11 achieved a predefined consensus (≥ 80%) in Delphi exercise and were classified as follows: (I) Gray-scale assessment [(A) non-specific synovial findings and (B) normal anatomical structures which can mimic synovial lesions due to either their low echogenicity or anisotropy]; (II) Doppler assessment [(A) Intra-articular normal vessels and (B) reverberation)]. Twenty-four corresponding examples with 49 still and 23 video images also achieved consensus. Our study provides a set of representative images that can help sonographers to understand false-positives in ultrasound scanning of synovitis and tenosynovitis.
Skin irritation, false positives and the local lymph node assay: a guideline issue?

PubMed

Basketter, David A; Kimber, Ian

2011-10-01

Since the formal validation and regulatory acceptance of the local lymph node assay (LLNA) there have been commentaries suggesting that the irritant properties of substances can give rise to false positives. As toxicology aspires to progress rapidly towards the age of in vitro alternatives, it is of increasing importance that issues relating to assay selectivity and performance are understood fully, and that true false positive responses are distinguished clearly from those that are simply unpalatable. In the present review, we have focused on whether skin irritation per se is actually a direct cause of true false positive results in the LLNA. The body of published work has been examined critically and considered in relation to our current understanding of the mechanisms of skin irritation and skin sensitisation. From these analyses it is very clear that, of itself, skin irritation is not a cause of false positive results. The corollary is, therefore, that limiting test concentrations in the LLNA for the purpose of avoiding skin irritation may lead, unintentionally, to false negatives. Where a substance is a true false positive in the LLNA, the classic example being sodium lauryl sulphate, explanations for that positivity will have to reach beyond the seductive, but incorrect, recourse to its skin irritation potential. Copyright © 2011 Elsevier Inc. All rights reserved.
Hypertension is strongly associated with false-positive bicycle exercise stress echocardiography testing results.

PubMed

Keller, Karsten; Stelzer, Kathrin; Munzel, Thomas; Ostad, Mir Abolfazl

2016-12-01

Exercise echocardiography is a reliable routine test in patients with known or suspected coronary artery disease. However, in ∼15% of all patients, stress echocardiography leads to false-positive stress echocardiography results. We aimed to investigate the impact of hypertension on stress echocardiographic results. We performed a retrospective study of patients with suspected or known stable coronary artery disease who underwent a bicycle exercise stress echocardiography. Patients with false-positive stress results were compared with those with appropriate results. 126 patients with suspected or known coronary artery disease were included in this retrospective study. 23 patients showed false-positive stress echocardiography results. Beside comparable age, gender distribution and coronary artery status, hypertension was more prevalent in patients with false-positive stress results (95.7% vs. 67.0%, p = 0.0410). Exercise peak load revealed a borderline-significance with lower loads in patients with false-positive results (100.0 (IQR 75.0/137.5) vs. 125.0 (100.0/150.0) W, p = 0.0601). Patients with false-positive stress results showed higher systolic (2.05 ± 0.69 vs. 1.67 ± 0.39 mmHg/W, p = 0.0193) and diastolic (1.03 ± 0.38 vs. 0.80 ± 0.28 mmHg/W, p = 0.0165) peak blood pressure (BP) per wattage. In a multivariate logistic regression test, hypertension (OR 17.6 [CI 95% 1.9-162.2], p = 0.0115), and systolic (OR 4.12 [1.56-10.89], p = 0.00430) and diastolic (OR 13.74 [2.46-76.83], p = 0.00285) peak BP per wattage, were associated with false-positive exercise results. ROC analysis for systolic and diastolic peak BP levels per wattage showed optimal cut-off values of 1.935mmHg/W and 0.823mmHg/W, indicating false-positive exercise echocardiographic results with AUCs of 0.660 and 0.664, respectively. Hypertension is a risk factor for false-positive stress exercise echocardiographic results in patients with known or suspected coronary artery disease. Presence of hypertension was associated with 17.6-fold elevated risk of false-positive results.
False Recognition in Behavioral Variant Frontotemporal Dementia and Alzheimer's Disease-Disinhibition or Amnesia?

PubMed

Flanagan, Emma C; Wong, Stephanie; Dutt, Aparna; Tu, Sicong; Bertoux, Maxime; Irish, Muireann; Piguet, Olivier; Rao, Sulakshana; Hodges, John R; Ghosh, Amitabha; Hornberger, Michael

2016-01-01

Episodic memory recall processes in Alzheimer's disease (AD) and behavioral variant frontotemporal dementia (bvFTD) can be similarly impaired, whereas recognition performance is more variable. A potential reason for this variability could be false-positive errors made on recognition trials and whether these errors are due to amnesia per se or a general over-endorsement of recognition items regardless of memory. The current study addressed this issue by analysing recognition performance on the Rey Auditory Verbal Learning Test (RAVLT) in 39 bvFTD, 77 AD and 61 control participants from two centers (India, Australia), as well as disinhibition assessed using the Hayling test. Whereas both AD and bvFTD patients were comparably impaired on delayed recall, bvFTD patients showed intact recognition performance in terms of the number of correct hits. However, both patient groups endorsed significantly more false-positives than controls, and bvFTD and AD patients scored equally poorly on a sensitivity index (correct hits-false-positives). Furthermore, measures of disinhibition were significantly associated with false positives in both groups, with a stronger relationship with false-positives in bvFTD. Voxel-based morphometry analyses revealed similar neural correlates of false positive endorsement across bvFTD and AD, with both patient groups showing involvement of prefrontal and Papez circuitry regions, such as medial temporal and thalamic regions, and a DTI analysis detected an emerging but non-significant trend between false positives and decreased fornix integrity in bvFTD only. These findings suggest that false-positive errors on recognition tests relate to similar mechanisms in bvFTD and AD, reflecting deficits in episodic memory processes and disinhibition. These findings highlight that current memory tests are not sufficient to accurately distinguish between bvFTD and AD patients.
False-positive buprenorphine EIA urine toxicology results due to high dose morphine: a case report.

PubMed

Tenore, Peter L

2012-01-01

In monitoring a patient with chronic pain who was taking high-dose morphine and oxycodone with weekly urine enzymatic immunoassay (EIA) toxicology testing, the authors noted consistent positives for buprenorphine. The patient was not taking buprenorphine, and gas chromatography/mass spectroscopy (GCMS) testing on multiple samples revealed no buprenorphine, indicating a case of false-positive buprenorphine EIAs in a high-dose opiate case. The authors discontinued oxycodone for a period of time and then discontinued morphine. Urine monitoring with EIAs and GCMS revealed false-positive buprenorphine EIAs, which remained only when the patient was taking morphine. When taking only oxycodone and no morphine, urine samples became buprenorphine negative. When morphine was reintroduced, false-positive buprenorphine results resumed. Medical practitioners should be aware that high-dose morphine (with morphine urine levels turning positive within the 15,000 to 28,000 mg/mL range) may produce false-positive buprenorphine EIAs with standard urine EIA toxicology testing.
Is screening with digital imaging using one retinal view adequate?

PubMed

Herbert, H M; Jordan, K; Flanagan, D W

2003-05-01

To compare the detection of diabetic retinopathy from digital images with slit-lamp biomicroscopy, and to determine whether British Diabetic Association (BDA) screening criteria are attained (>80% sensitivity, >95% specificity, &<5% technical failure). Diabetics referred for screening were studied in a prospective fashion. A single 45 degrees fundus image was obtained using the nonmydriatic digital camera. Each patient subsequently underwent slit-lamp biomicroscopy and diabetic retinopathy grading by a consultant ophthalmologist. Diabetic retinopathy and maculopathy was graded according to the Early Treatment of Diabetic Retinopathy Study. A total of 145 patients (288 eyes) were identified for screening. Of these, 26% of eyes had diabetic retinopathy, and eight eyes (3%) had sight-threatening diabetic retinopathy requiring treatment. The sensitivity for detection of any diabetic retinopathy was 38% and the specificity 95%. There was a 4% technical failure rate. There were 42/288 false negatives and 10/288 false positives. Of the 42 false negatives, 18 represented diabetic maculopathy, 20 represented peripheral diabetic retinopathy and four eyes had both macular and peripheral changes. Three eyes in the false-negative group (1% of total eyes) had sight-threatening retinopathy. There was good concordance between the two consultants (79% agreement on slit-lamp biomicroscopy and 84% on digital image interpretation). The specificity value and technical failure rate compare favourably with BDA guidelines. The low sensitivity for detection of any retinopathy reflects failure to detect minimal maculopathy and retinopathy outside the 45 degrees image. This could be improved by an additional nasal image and careful evaluation of macular images with a low threshold for slit-lamp biomicroscopy if image quality is poor.

New insights into the biogenesis of nuclear RNA polymerases?

PubMed

Cloutier, Philippe; Coulombe, Benoit

2010-04-01

More than 30 years of research on nuclear RNA polymerases (RNAP I, II, and III) has uncovered numerous factors that regulate the activity of these enzymes during the transcription reaction. However, very little is known about the machinery that regulates the fate of RNAPs before or after transcription. In particular, the mechanisms of biogenesis of the 3 nuclear RNAPs, which comprise both common and specific subunits, remains mostly uncharacterized and the proteins involved are yet to be discovered. Using protein affinity purification coupled to mass spectrometry (AP-MS), we recently unraveled a high-density interaction network formed by nuclear RNAP subunits from the soluble fraction of human cell extracts. Validation of the dataset using a machine learning approach trained to minimize the rate of false positives and false negatives yielded a high-confidence dataset and uncovered novel interactors that regulate the RNAP II transcription machinery, including a set of proteins we named the RNAP II-associated proteins (RPAPs). One of the RPAPs, RPAP3, is part of an 11-subunit complex we termed the RPAP3/R2TP/prefoldin-like complex. Here, we review the literature on the subunits of this complex, which points to a role in nuclear RNAP biogenesis.
Impact of sentinel lymph node biopsy on immediate breast reconstruction after mastectomy.

PubMed

Wood, Benjamin C; David, Lisa R; Defranzo, Anthony J; Stewart, John H; Shen, Perry; Geisinger, Kim R; Marks, Malcolm W; Levine, Edward A

2009-07-01

Traditionally, sentinel lymph node biopsy (SLNB) is performed at the time of mastectomy and reconstruction. However, several groups have advocated SLNB as a separate outpatient procedure before mastectomy, when immediate reconstruction is planned, to allow for complete pathologic evaluation. The purpose of this study was to determine the impact of intraoperative analysis of SLNB on the reconstructive plan when performed at the same time as definitive surgery. A retrospective review was conducted of all mastectomy cases performed at a single institution between September 1998 and November 2007. Of the 747 mastectomy cases reviewed, SLNB was conducted in 344 cases, and there was immediate breast reconstruction in 193 of those cases. There were 27 (7.8%) false negative and three (0.9%) false positive intraoperative analysis of SLNB. Touch preparation analysis from the SLNB changed the reconstructive plan in four (2.1%) cases. In our experience, SLNB can be performed at the time of mastectomy with minimal impact on the reconstructive plan. A staged approach incurs significant additional expense, increases the delay in initiation of systemic therapy and the propensity of procedure-related morbidity; therefore, SLNB should not be performed as a separate procedure before definitive surgery with immediate breast reconstruction.
New insights into the biogenesis of nuclear RNA polymerases?1

PubMed Central

Cloutier, Philippe; Coulombe, Benoit

2015-01-01

More than 30 years of research on nuclear RNA polymerases (RNAP I, II, and III) has uncovered numerous factors that regulate the activity of these enzymes during the transcription reaction. However, very little is known about the machinery that regulates the fate of RNAPs before or after transcription. In particular, the mechanisms of biogenesis of the 3 nuclear RNAPs, which comprise both common and specific subunits, remains mostly uncharacterized and the proteins involved are yet to be discovered. Using protein affinity purification coupled to mass spectrometry (AP–MS), we recently unraveled a high-density interaction network formed by nuclear RNAP subunits from the soluble fraction of human cell extracts. Validation of the dataset using a machine learning approach trained to minimize the rate of false positives and false negatives yielded a high-confidence dataset and uncovered novel interactors that regulate the RNAP II transcription machinery, including a set of proteins we named the RNAP II-associated proteins (RPAPs). One of the RPAPs, RPAP3, is part of an 11-subunit complex we termed the RPAP3/R2TP/prefoldin-like complex. Here, we review the literature on the subunits of this complex, which points to a role in nuclear RNAP biogenesis. PMID:20453924
An UGS radar with micro-Doppler capabilities for wide area persistent surveillance

NASA Astrophysics Data System (ADS)

Tahmoush, Dave; Silvious, Jerry; Clark, John

2010-04-01

Detecting humans and distinguishing them from natural fauna is an important issue in security applications to reduce false alarm rates. In particular, it is important to detect and classify people who are walking in remote locations and transmit back detections over extended periods at a low cost and with minimal maintenance. The ability to discriminate men versus animals and vehicles at long range would give a distinct sensor advantage. The reduction in false positive detections due to animals would increase the usefulness of detections, while dismount identification could reduce friendly-fire. We developed and demonstrate a compact radar technology that is scalable to a variety of ultra-lightweight and low-power platforms for wide area persistent surveillance as an unattended, unmanned, and man-portable ground sensor. The radar uses micro-Doppler processing to characterize the tracks of moving targets and to then eliminate unimportant detections due to animals or civilian activity. This paper presents the system and data on humans, vehicles, and animals at multiple angles and directions of motion, demonstrates the signal processing approach that makes the targets visually recognizable, and verifies that the UGS radar has enough micro-Doppler capability to distinguish between humans, vehicles, and animals.
Video redaction: a survey and comparison of enabling technologies

NASA Astrophysics Data System (ADS)

Sah, Shagan; Shringi, Ameya; Ptucha, Raymond; Burry, Aaron; Loce, Robert

2017-09-01

With the prevalence of video recordings from smart phones, dash cams, body cams, and conventional surveillance cameras, privacy protection has become a major concern, especially in light of legislation such as the Freedom of Information Act. Video redaction is used to obfuscate sensitive and personally identifiable information. Today's typical workflow involves simple detection, tracking, and manual intervention. Automated methods rely on accurate detection mechanisms being paired with robust tracking methods across the video sequence to ensure the redaction of all sensitive information while minimizing spurious obfuscations. Recent studies have explored the use of convolution neural networks and recurrent neural networks for object detection and tracking. The present paper reviews the redaction problem and compares a few state-of-the-art detection, tracking, and obfuscation methods as they relate to redaction. The comparison introduces an evaluation metric that is specific to video redaction performance. The metric can be evaluated in a manner that allows balancing the penalty for false negatives and false positives according to the needs of particular application, thereby assisting in the selection of component methods and their associated hyperparameters such that the redacted video has fewer frames that require manual review.
Performing IgE serum testing due to bioinformatics matches in the allergenicity assessment of GM crops.

PubMed

Goodman, Richard E

2008-10-01

Proteins introduced into genetically modified (GM) organisms through genetic engineering must be evaluated for their potential to cause allergic disease under various national laws and regulations. The Codex Alimentarius Commission guidance document (2003) calls for testing of serum IgE binding to the introduced protein if the gene was from an allergenic source, or the sequence of the transferred protein has >35% identity in any segment of 80 or more amino acids to a known allergen or shares significant short amino acid identities. The Codex guidance recognized that the assessment will evolve based on new scientific knowledge. Arguably, the current criteria are too conservative as discussed in this paper and they do not provide practical guidance on serum testing. The goals of this paper are: (1) to summarize evidence supporting the level of identity that indicates potential risk of cross-reactivity for those with existing allergies; (2) to provide example bioinformatics results and discuss their interpretation using published examples of proteins expressed in transgenic crops; and (3) to discuss key factors of experimental design and methodology for serum IgE tests to minimize the rate of false negative and false positive identification of potential allergens and cross-reactive proteins.
Diurnal rhythm and concordance between objective and subjective hot flashes: the Hilo Women's Health Study.

PubMed

Sievert, Lynnette L; Reza, Angela; Mills, Phoebe; Morrison, Lynn; Rahberg, Nichole; Goodloe, Amber; Sutherland, Michael; Brown, Daniel E

2010-01-01

The aims of this study were to test for a diurnal pattern in hot flashes in a multiethnic population living in a hot, humid environment and to examine the rates of concordance between objective and subjective measures of hot flashes using ambulatory and laboratory measures. Study participants aged 45 to 55 years were recruited from the general population of Hilo, HI. Women wore a Biolog hot flash monitor (UFI, Morro Bay, CA), kept a diary for 24 hours, and also participated in 3-hour laboratory measures (n = 199). Diurnal patterns were assessed using polynomial regression. For each woman, objectively recorded hot flashes that matched subjective experience were treated as true-positive readings. Subjective hot flashes were considered the standard for computing false-positive and false-negative readings. True-positive, false-positive, and false-negative readings were compared across ethnic groups by chi analyses. Frequencies of sternal, nuchal, and subjective hot flashes peaked at 1500 +/- 1 hours with no difference by ethnicity. Laboratory results supported the pattern seen in ambulatory monitoring. Sternal and nuchal monitoring showed the same frequency of true-positive measures, but nonsternal electrodes picked up more false-positive readings. Laboratory monitoring showed very low frequencies of false negatives. There were no ethnic differences in the frequency of true-positive or false-positive measures. Women of European descent were more likely to report hot flashes that were not objectively demonstrated (false-negative measures). The diurnal pattern and peak in hot flash occurrence in the hot humid environment of Hilo were similar to results from more temperate environments. Lack of variation in sternal versus nonsternal measures and in true-positive measures across ethnicities suggests no appreciable effect of population variation in sweating patterns.
Diurnal rhythm and concordance between objective and subjective hot flashes: The Hilo Women’s Health Study

PubMed Central

Sievert, Lynnette L.; Reza, Angela; Mills, Phoebe; Morrison, Lynn; Rahberg, Nichole; Goodloe, Amber; Sutherland, Michael; Brown, Daniel E.

2010-01-01

Objective To test for a diurnal pattern in hot flashes in a multi-ethnic population living in a hot, humid environment. To examine rates of concordance between objective and subjective measures of hot flashes using ambulatory and laboratory measures. Methods Study participants aged 45–55 were recruited from the general population of Hilo, Hawaii. Women wore a Biolog hot flash monitor, kept a diary for 24-hours, and also participated in 3-hour laboratory measures (n=199). Diurnal patterns were assessed using polynomial regression. For each woman, objectively recorded hot flashes that matched subjective experience were treated as true positive readings. Subjective hot flashes were considered the standard for computing false positive and false negative readings. True positive, false positive, and false negative readings were compared across ethnic groups by chi-square analyses. Results Frequencies of sternal, nuchal and subjective hot flashes peaked at 15:00 ± 1 hour with no difference by ethnicity. Laboratory results supported the pattern seen in ambulatory monitoring. Sternal and nuchal monitoring showed the same frequency of true positive measures, but non-sternal electrodes picked up more false positive readings. Laboratory monitoring showed very low frequencies of false negatives. There were no ethnic differences in the frequency of true positive or false positive measures. Women of European descent were more likely to report hot flashes that were not objectively demonstrated (false negative measures). Conclusions The diurnal pattern and peak in hot flash occurrence in the hot humid environment of Hilo was similar to results from more temperate environments. Lack of variation in sternal vs. non-sternal measures, and in true positive measures across ethnicities suggests no appreciable effect of population variation in sweating patterns. PMID:20220538
Ignoring Intermarker Linkage Disequilibrium Induces False-Positive Evidence of Linkage for Consanguineous Pedigrees when Genotype Data Is Missing for Any Pedigree Member

PubMed Central

Li, Bingshan; Leal, Suzanne M.

2008-01-01

Missing genotype data can increase false-positive evidence for linkage when either parametric or nonparametric analysis is carried out ignoring intermarker linkage disequilibrium (LD). Previously it was demonstrated by Huang et al. [1] that no bias occurs in this situation for affected sib-pairs with unrelated parents when either both parents are genotyped or genotype data is available for two additional unaffected siblings when parental genotypes are missing. However, this is not the case for autosomal recessive consanguineous pedigrees, where missing genotype data for any pedigree member within a consanguinity loop can increase false-positive evidence of linkage. False-positive evidence for linkage is further increased when cryptic consanguinity is present. The amount of false-positive evidence for linkage, and which family members aid in its reduction, is highly dependent on which family members are genotyped. When parental genotype data is available, the false-positive evidence for linkage is usually not as strong as when parental genotype data is unavailable. For a pedigree with an affected proband whose first-cousin parents have been genotyped, further reduction in the false-positive evidence of linkage can be obtained by including genotype data from additional affected siblings of the proband or genotype data from the proband's sibling-grandparents. For the situation, when parental genotypes are unavailable, false-positive evidence for linkage can be reduced by including genotype data from either unaffected siblings of the proband or the proband's married-in-grandparents in the analysis. PMID:18073490
Biological false-positive venereal disease research laboratory test in cerebrospinal fluid in the diagnosis of neurosyphilis - a case-control study.

PubMed

Zheng, S; Lin, R J; Chan, Y H; Ngan, C C L

2018-03-01

There is no clear consensus on the diagnosis of neurosyphilis. The Venereal Disease Research Laboratory (VDRL) test from cerebrospinal fluid (CSF) has traditionally been considered the gold standard for diagnosing neurosyphilis but is widely known to be insensitive. In this study, we compared the clinical and laboratory characteristics of true-positive VDRL-CSF cases with biological false-positive VDRL-CSF cases. We retrospectively identified cases of true and false-positive VDRL-CSF across a 3-year period received by the Immunology and Serology Laboratory, Singapore General Hospital. A biological false-positive VDRL-CSF is defined as a reactive VDRL-CSF with a non-reactive Treponema pallidum particle agglutination (TPPA)-CSF and/or negative Line Immuno Assay (LIA)-CSF IgG. A true-positive VDRL-CSF is a reactive VDRL-CSF with a concordant reactive TPPA-CSF and/or positive LIA-CSF IgG. During the study period, a total of 1254 specimens underwent VDRL-CSF examination. Amongst these, 60 specimens from 53 patients tested positive for VDRL-CSF. Of the 53 patients, 42 (79.2%) were true-positive cases and 11 (20.8%) were false-positive cases. In our setting, a positive non-treponemal serology has 97.6% sensitivity, 100% specificity, 100% positive predictive value and 91.7% negative predictive value for a true-positive VDRL-CSF based on our laboratory definition. HIV seropositivity was an independent predictor of a true-positive VDRL-CSF. Biological false-positive VDRL-CSF is common in a setting where patients are tested without first establishing a serological diagnosis of syphilis. Serological testing should be performed prior to CSF evaluation for neurosyphilis. © 2017 European Academy of Dermatology and Venereology.
Early identification of microorganisms in blood culture prior to the detection of a positive signal in the BACTEC FX system using matrix-assisted laser desorption/ionization-time of flight mass spectrometry.

PubMed

Wang, Ming-Cheng; Lin, Wei-Hung; Yan, Jing-Jou; Fang, Hsin-Yi; Kuo, Te-Hui; Tseng, Chin-Chung; Wu, Jiunn-Jong

2015-08-01

Matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) is a valuable method for rapid identification of blood stream infection (BSI) pathogens. Integration of MALDI-TOF MS and blood culture system can speed the identification of causative BSI microorganisms. We investigated the minimal microorganism concentrations of common BSI pathogens required for positive blood culture using BACTEC FX and for positive identification using MALDI-TOF MS. The time to detection with positive BACTEC FX and minimal incubation time with positive MALDI-TOF MS identification were determined for earlier identification of common BSI pathogens. The minimal microorganism concentrations required for positive blood culture using BACTEC FX were >10(7)-10(8) colony forming units/mL for most of the BSI pathogens. The minimal microorganism concentrations required for identification using MALDI-TOF MS were > 10(7) colony forming units/mL. Using simulated BSI models, one can obtain enough bacterial concentration from blood culture bottles for successful identification of five common Gram-positive and Gram-negative bacteria using MALDI-TOF MS 1.7-2.3 hours earlier than the usual time to detection in blood culture systems. This study provides an approach to earlier identification of BSI pathogens prior to the detection of a positive signal in the blood culture system using MALDI-TOF MS, compared to current methods. It can speed the time for identification of BSI pathogens and may have benefits of earlier therapy choice and on patient outcome. Copyright © 2013. Published by Elsevier B.V.
False positive circumsporozoite protein ELISA: a challenge for the estimation of the entomological inoculation rate of malaria and for vector incrimination

PubMed Central

2011-01-01

Background The entomological inoculation rate (EIR) is an important indicator in estimating malaria transmission and the impact of vector control. To assess the EIR, the enzyme-linked immunosorbent assay (ELISA) to detect the circumsporozoite protein (CSP) is increasingly used. However, several studies have reported false positive results in this ELISA. The false positive results could lead to an overestimation of the EIR. The aim of present study was to estimate the level of false positivity among different anopheline species in Cambodia and Vietnam and to check for the presence of other parasites that might interact with the anti-CSP monoclonal antibodies. Methods Mosquitoes collected in Cambodia and Vietnam were identified and tested for the presence of sporozoites in head and thorax by using CSP-ELISA. ELISA positive samples were confirmed by a Plasmodium specific PCR. False positive mosquitoes were checked by PCR for the presence of parasites belonging to the Haemosporidia, Trypanosomatidae, Piroplasmida, and Haemogregarines. The heat-stability and the presence of the cross-reacting antigen in the abdomen of the mosquitoes were also checked. Results Specimens (N = 16,160) of seven anopheline species were tested by CSP-ELISA for Plasmodium falciparum and Plasmodium vivax (Pv210 and Pv247). Two new vector species were identified for the region: Anopheles pampanai (P. vivax) and Anopheles barbirostris (Plasmodium malariae). In 88% (155/176) of the mosquitoes found positive with the P. falciparum CSP-ELISA, the presence of Plasmodium sporozoites could not be confirmed by PCR. This percentage was much lower (28% or 5/18) for P. vivax CSP-ELISAs. False positive CSP-ELISA results were associated with zoophilic mosquito species. None of the targeted parasites could be detected in these CSP-ELISA false positive mosquitoes. The ELISA reacting antigen of P. falciparum was heat-stable in CSP-ELISA true positive specimens, but not in the false positives. The heat-unstable cross-reacting antigen is mainly present in head and thorax and almost absent in the abdomens (4 out of 147) of the false positive specimens. Conclusion The CSP-ELISA can considerably overestimate the EIR, particularly for P. falciparum and for zoophilic species. The heat-unstable cross-reacting antigen in false positives remains unknown. Therefore it is highly recommended to confirm all positive CSP-ELISA results, either by re-analysing the heated ELISA lysate (100°C, 10 min), or by performing Plasmodium specific PCR followed if possible by sequencing of the amplicons for Plasmodium species determination. PMID:21767376
77 FR 48045 - Supplemental Nutrition Assistance Program: Disqualified Recipient Reporting and Computer Matching...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-08-13

... false positive match rate of 10 percent. Making the match mandatory for the States who did not perform... number of prisoners from 1995 to 2013 and assumed a 10 percent false positive match rate. Finally, we... matches are false positives. We estimate that mandatory matches at certification will identify an...
Minimal massive 3D gravity

NASA Astrophysics Data System (ADS)

Bergshoeff, Eric; Hohm, Olaf; Merbis, Wout; Routh, Alasdair J.; Townsend, Paul K.

2014-07-01

We present an alternative to topologically massive gravity (TMG) with the same ‘minimal’ bulk properties; i.e. a single local degree of freedom that is realized as a massive graviton in linearization about an anti-de Sitter (AdS) vacuum. However, in contrast to TMG, the new ‘minimal massive gravity’ has both a positive energy graviton and positive central charges for the asymptotic AdS-boundary conformal algebra.
Bladder cancer diagnosis with CT urography: test characteristics and reasons for false-positive and false-negative results.

PubMed

Trinh, Tony W; Glazer, Daniel I; Sadow, Cheryl A; Sahni, V Anik; Geller, Nina L; Silverman, Stuart G

2018-03-01

To determine test characteristics of CT urography for detecting bladder cancer in patients with hematuria and those undergoing surveillance, and to analyze reasons for false-positive and false-negative results. A HIPAA-compliant, IRB-approved retrospective review of reports from 1623 CT urograms between 10/2010 and 12/31/2013 was performed. 710 examinations for hematuria or bladder cancer history were compared to cystoscopy performed within 6 months. Reference standard was surgical pathology or 1-year minimum clinical follow-up. False-positive and false-negative examinations were reviewed to determine reasons for errors. Ninety-five bladder cancers were detected. CT urography accuracy: was 91.5% (650/710), sensitivity 86.3% (82/95), specificity 92.4% (568/615), positive predictive value 63.6% (82/129), and negative predictive value was 97.8% (568/581). Of 43 false positives, the majority of interpretation errors were due to benign prostatic hyperplasia (n = 12), trabeculated bladder (n = 9), and treatment changes (n = 8). Other causes include blood clots, mistaken normal anatomy, infectious/inflammatory changes, or had no cystoscopic correlate. Of 13 false negatives, 11 were due to technique, one to a large urinary residual, one to artifact. There were no errors in perception. CT urography is an accurate test for diagnosing bladder cancer; however, in protocols relying predominantly on excretory phase images, overall sensitivity remains insufficient to obviate cystoscopy. Awareness of bladder cancer mimics may reduce false-positive results. Improvements in CTU technique may reduce false-negative results.
Methods for threshold determination in multiplexed assays

DOEpatents

Tammero, Lance F. Bentley; Dzenitis, John M; Hindson, Benjamin J

2014-06-24

Methods for determination of threshold values of signatures comprised in an assay are described. Each signature enables detection of a target. The methods determine a probability density function of negative samples and a corresponding false positive rate curve. A false positive criterion is established and a threshold for that signature is determined as a point at which the false positive rate curve intersects the false positive criterion. A method for quantitative analysis and interpretation of assay results together with a method for determination of a desired limit of detection of a signature in an assay are also described.
Shear-wave elastography in the diagnosis of solid breast masses: what leads to false-negative or false-positive results?

PubMed

Yoon, Jung Hyun; Jung, Hae Kyoung; Lee, Jong Tae; Ko, Kyung Hee

2013-09-01

To investigate the factors that have an effect on false-positive or false-negative shear-wave elastography (SWE) results in solid breast masses. From June to December 2012, 222 breast lesions of 199 consecutive women (mean age: 45.3 ± 10.1 years; range, 21 to 88 years) who had been scheduled for biopsy or surgical excision were included. Greyscale ultrasound and SWE were performed in all women before biopsy. Final ultrasound assessments and SWE parameters (pattern classification and maximum elasticity) were recorded and compared with histopathology results. Patient and lesion factors in the 'true' and 'false' groups were compared. Of the 222 masses, 175 (78.8 %) were benign, and 47 (21.2 %) were malignant. False-positive rates of benign masses were significantly higher than false-negative rates of malignancy in SWE patterns, 36.6 % to 6.4 % (P < 0.001). Among both benign and malignant masses, factors showing significance among false SWE features were lesion size, breast thickness and lesion depth (all P < 0.05). All 47 malignant breast masses had SWE images of good quality. False SWE features were more significantly seen in benign masses. Lesion size, breast thickness and lesion depth have significance in producing false results, and this needs consideration in SWE image acquisition. • Shear-wave elastography (SWE) is widely used during breast imaging • At SWE, false-positive rates were significantly higher than false-negative rates • Larger size, breast thickness, depth and fair quality influences false-positive SWE features • Smaller size, larger breast thickness and depth influences false-negative SWE features.
Variation in aluminium patch test reactivity over time.

PubMed

Siemund, Ingrid; Mowitz, Martin; Zimerson, Erik; Bruze, Magnus; Hindsén, Monica

2017-11-01

Contact allergy to aluminium has been reported more frequently in recent years. It has been pointed out that positive patch test reactions to aluminium may not be reproducible on retesting. To investigate possible variations in patch test reactivity to aluminium over time. Twenty-one adults, who had previously reacted positively to aluminium, were patch tested with equimolar dilution series in pet. of aluminium chloride hexahydrate and aluminium lactate, four times over a period of 8 months. Thirty-six of 84 (43%) serial dilution tests with aluminium chloride hexahydrate and 49 of 84 (58%) serial dilution tests with aluminium lactate gave negative results. The range of reactivity varied between a negative reaction to aluminium chloride hexahydrate at 10% and/or to aluminium lactate at 12%, and a positive reaction to aluminium chloride hexahydrate at 0.1% and/or to aluminium lactate at 0.12%. The highest individual difference in test reactivity noticed was 320-fold when the two most divergent minimal eliciting concentrations were compared. The patch test reactivity to aluminium varies over time. Aluminium-allergic individuals may have false-negative reactions. Therefore, retesting with aluminium should be considered when there is a strong suspicion of aluminium contact allergy. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.
Sensitive and comprehensive detection of chemical warfare agents in air by atmospheric pressure chemical ionization ion trap tandem mass spectrometry with counterflow introduction.

PubMed

Seto, Yasuo; Sekiguchi, Hiroshi; Maruko, Hisashi; Yamashiro, Shigeharu; Sano, Yasuhiro; Takayama, Yasuo; Sekioka, Ryoji; Yamaguchi, Shintaro; Kishi, Shintaro; Satoh, Takafumi; Sekiguchi, Hiroyuki; Iura, Kazumitsu; Nagashima, Hisayuki; Nagoya, Tomoki; Tsuge, Kouichiro; Ohsawa, Isaac; Okumura, Akihiko; Takada, Yasuaki; Ezawa, Naoya; Watanabe, Susumu; Hashimoto, Hiroaki

2014-05-06

A highly sensitive and specific real-time field-deployable detection technology, based on counterflow air introduction atmospheric pressure chemical ionization, has been developed for a wide range of chemical warfare agents (CWAs) comprising gaseous (two blood agents, three choking agents), volatile (six nerve gases and one precursor agent, five blister agents), and nonvolatile (three lachrymators, three vomiting agents) agents in air. The approach can afford effective chemical ionization, in both positive and negative ion modes, for ion trap multiple-stage mass spectrometry (MS(n)). The volatile and nonvolatile CWAs tested provided characteristic ions, which were fragmented into MS(3) product ions in positive and negative ion modes. Portions of the fragment ions were assigned by laboratory hybrid mass spectrometry (MS) composed of linear ion trap and high-resolution mass spectrometers. Gaseous agents were detected by MS or MS(2) in negative ion mode. The limits of detection for a 1 s measurement were typically at or below the microgram per cubic meter level except for chloropicrin (submilligram per cubic meter). Matrix effects by gasoline vapor resulted in minimal false-positive signals for all the CWAs and some signal suppression in the case of mustard gas. The moisture level did influence the measurement of the CWAs.
Ground state of high-density matter

NASA Technical Reports Server (NTRS)

Copeland, ED; Kolb, Edward W.; Lee, Kimyeong

1988-01-01

It is shown that if an upper bound to the false vacuum energy of the electroweak Higgs potential is satisfied, the true ground state of high-density matter is not nuclear matter, or even strange-quark matter, but rather a non-topological soliton where the electroweak symmetry is exact and the fermions are massless. This possibility is examined in the standard SU(3) sub C tensor product SU(2) sub L tensor product U(1) sub Y model. The bound to the false vacuum energy is satisfied only for a narrow range of the Higgs boson masses in the minimal electroweak model (within about 10 eV of its minimum allowed value of 6.6 GeV) and a somewhat wider range for electroweak models with a non-minimal Higgs sector.

Efficacy of an opposite position aspiration on resolution of pneumothorax following CT-guided lung biopsy

PubMed Central

Zeng, L-C; Du, Y; Yang, H-F; Xie, M-G; Liao, H-Q; Zhang, Y-D; Li, L; Wang, Q; Hu, L

2015-01-01

Objective: To evaluate the efficacy of aspiration in an opposite position to deal with pneumothorax after CT-guided lung biopsy. Methods: A retrospective study was developed involving 210 patients with pneumothorax who had undergone CT-guided percutaneous core biopsies from January 2012 to March 2014 for various pulmonary lesions. Asymptomatic patients with minimal pneumothorax were treated conservatively. Simple manual aspiration was performed for symptomatic patients with minimal pneumothorax and for all patients with moderate to large pneumothorax. An opposite position aspiration was performed when simple manual aspiration failed. The efficacy of simple manual aspiration and the opposite position aspiration was observed. Results: Among 210 patients with pneumothorax, 128 (61.0%) asymptomatic patients with minimal pneumothorax were treated conservatively. The remaining 82 were treated with attempted simple manual aspiration. Out of these 82 patients, simple manual aspiration was successful in 58 (70.7%, 58/82) cases. The complete and partial regression rates were 17.2% (10/58) and 82.8% (48/58), respectively. In the other 24 patients (29.3%, 24/82), simple aspiration technique was ineffective. An opposite position (from prone to supine or vice versa) was applied, and a new biopsy puncture site was chosen for reaspiration. This procedure was successful in 22 patients but not in 2 patients who had to have a chest tube insertion. The complete and partial regression rates were 25.0% (6/24) and 66.7% (16/24), respectively. Applying the new method, the total effective rate of aspiration improved significantly from 70.7% (58/82) to 97.6% (80/82). Conclusion: The opposite position aspiration can be safe, effective and minimally invasive treatment for CT-guided lung biopsy-induced pneumothorax thus reducing the use of chest tube significantly. Advances in knowledge: (1) Opposite position aspiration can elevate the success rate of aspiration significantly (from 70.7% to 97.6% in our study); (2) this procedure is a safe, effective and minimally invasive treatment for pneumothorax caused by biopsy; and (3) opposite position aspiration is a useful technique to reduce the use of chest tube, which has clinical significance. PMID:25966292
Factors affecting urine reagent strip blood results in dogs and nonhuman primates and interpretation of urinalysis in preclinical toxicology studies: a Multi-Institution Contract Research Organization and BioPharmaceutical Company Perspective.

PubMed

Aulbach, Adam D; Schultze, Eric; Tripathi, Niraj K; Hall, Robert L; Logan, Michael R; Meyer, Denny J

2015-06-01

Urinalysis data in preclinical toxicology studies can be influenced by preanalytic and analytic factors which have the potential to confound interpretation. There is a paucity of information regarding positive reagent strip urinary blood reactions in healthy nonhuman primates (NHP) and Beagle dogs used in preclinical toxicology studies. The objectives were (1) to establish historical control data for reagent strip urinary blood reactions in healthy NHP and Beagle dogs, (2) to determine the incidence of positive urinary blood reactions during predose and dosing phases, and (3) to determine if collection practice was a relevant parameter. Historical control data from 2 institutions in the biopharmaceutical industry were retrospectively analyzed for reagent strip urinary blood reactions in healthy NHP and Beagles. The incidence of positive results between the 2 institutions with different urine collection practices and between males and females was compared. The incidence of positive urinary blood reactions in NHP was comparable between institutions (≤ 14% in males; ≤ 33% in females), while the incidence of positive urinary blood reactions in Beagles was more variable (≤ 77% in males; ≤ 69% in females), and higher in females during the dosing phase. Positive urinary blood results that could potentially be misinterpreted as toxicologically relevant were identified in healthy NHP and Beagles during predose and dosing phases. Different incidences of positive results between the 2 institutions were likely related to collection practices. Strategies to reduce feces and food contamination of collected urine samples should help minimize false-positive urinary blood reactions. © 2015 American Society for Veterinary Clinical Pathology.
Multiplexing of ChIP-Seq Samples in an Optimized Experimental Condition Has Minimal Impact on Peak Detection.

PubMed

Kacmarczyk, Thadeous J; Bourque, Caitlin; Zhang, Xihui; Jiang, Yanwen; Houvras, Yariv; Alonso, Alicia; Betel, Doron

2015-01-01

Multiplexing samples in sequencing experiments is a common approach to maximize information yield while minimizing cost. In most cases the number of samples that are multiplexed is determined by financial consideration or experimental convenience, with limited understanding on the effects on the experimental results. Here we set to examine the impact of multiplexing ChIP-seq experiments on the ability to identify a specific epigenetic modification. We performed peak detection analyses to determine the effects of multiplexing. These include false discovery rates, size, position and statistical significance of peak detection, and changes in gene annotation. We found that, for histone marker H3K4me3, one can multiplex up to 8 samples (7 IP + 1 input) at ~21 million single-end reads each and still detect over 90% of all peaks found when using a full lane for sample (~181 million reads). Furthermore, there are no variations introduced by indexing or lane batch effects and importantly there is no significant reduction in the number of genes with neighboring H3K4me3 peaks. We conclude that, for a well characterized antibody and, therefore, model IP condition, multiplexing 8 samples per lane is sufficient to capture most of the biological signal.
Multiplexing of ChIP-Seq Samples in an Optimized Experimental Condition Has Minimal Impact on Peak Detection

PubMed Central

Kacmarczyk, Thadeous J.; Bourque, Caitlin; Zhang, Xihui; Jiang, Yanwen; Houvras, Yariv; Alonso, Alicia; Betel, Doron

2015-01-01

Multiplexing samples in sequencing experiments is a common approach to maximize information yield while minimizing cost. In most cases the number of samples that are multiplexed is determined by financial consideration or experimental convenience, with limited understanding on the effects on the experimental results. Here we set to examine the impact of multiplexing ChIP-seq experiments on the ability to identify a specific epigenetic modification. We performed peak detection analyses to determine the effects of multiplexing. These include false discovery rates, size, position and statistical significance of peak detection, and changes in gene annotation. We found that, for histone marker H3K4me3, one can multiplex up to 8 samples (7 IP + 1 input) at ~21 million single-end reads each and still detect over 90% of all peaks found when using a full lane for sample (~181 million reads). Furthermore, there are no variations introduced by indexing or lane batch effects and importantly there is no significant reduction in the number of genes with neighboring H3K4me3 peaks. We conclude that, for a well characterized antibody and, therefore, model IP condition, multiplexing 8 samples per lane is sufficient to capture most of the biological signal. PMID:26066343
Reducing false positives of microcalcification detection systems by removal of breast arterial calcifications.

PubMed

Mordang, Jan-Jurre; Gubern-Mérida, Albert; den Heeten, Gerard; Karssemeijer, Nico

2016-04-01

In the past decades, computer-aided detection (CADe) systems have been developed to aid screening radiologists in the detection of malignant microcalcifications. These systems are useful to avoid perceptual oversights and can increase the radiologists' detection rate. However, due to the high number of false positives marked by these CADe systems, they are not yet suitable as an independent reader. Breast arterial calcifications (BACs) are one of the most frequent false positives marked by CADe systems. In this study, a method is proposed for the elimination of BACs as positive findings. Removal of these false positives will increase the performance of the CADe system in finding malignant microcalcifications. A multistage method is proposed for the removal of BAC findings. The first stage consists of a microcalcification candidate selection, segmentation and grouping of the microcalcifications, and classification to remove obvious false positives. In the second stage, a case-based selection is applied where cases are selected which contain BACs. In the final stage, BACs are removed from the selected cases. The BACs removal stage consists of a GentleBoost classifier trained on microcalcification features describing their shape, topology, and texture. Additionally, novel features are introduced to discriminate BACs from other positive findings. The CADe system was evaluated with and without BACs removal. Here, both systems were applied on a validation set containing 1088 cases of which 95 cases contained malignant microcalcifications. After bootstrapping, free-response receiver operating characteristics and receiver operating characteristics analyses were carried out. Performance between the two systems was compared at 0.98 and 0.95 specificity. At a specificity of 0.98, the sensitivity increased from 37% to 52% and the sensitivity increased from 62% up to 76% at a specificity of 0.95. Partial areas under the curve in the specificity range of 0.8-1.0 were significantly different between the system without BACs removal and the system with BACs removal, 0.129 ± 0.009 versus 0.144 ± 0.008 (p<0.05), respectively. Additionally, the sensitivity at one false positive per 50 cases and one false positive per 25 cases increased as well, 37% versus 51% (p<0.05) and 58% versus 67% (p<0.05) sensitivity, respectively. Additionally, the CADe system with BACs removal reduces the number of false positives per case by 29% on average. The same sensitivity at one false positive per 50 cases in the CADe system without BACs removal can be achieved at one false positive per 80 cases in the CADe system with BACs removal. By using dedicated algorithms to detect and remove breast arterial calcifications, the performance of CADe systems can be improved, in particular, at false positive rates representative for operating points used in screening.
Effects of depressive disorder on false memory for emotional information.

PubMed

Yeh, Zai-Ting; Hua, Mau-Sun

2009-01-01

This study explored with a false memory paradigm whether (1) depressed patients revealed more false memories and (2) whether more negative false than positive false recognition existed in subjects with depressive disorders. Thirty-two patients suffering from a major depressive episode (DSM-IV criteria), and 30 age- and education-matched normal control subjects participated in this study. After the presentation of a list of positive, negative, and neutral association items in the learning phase, subjects were asked to give a yes/no response in the recognition phase. They were also asked to rate 81 recognition items with emotional valence scores. The results revealed more negative false memories in the clinical depression group than in the normal control group; however, we did not find more negative false memories than positive ones in patients. When compared with the normal group, a more conservative response criterion for positive items was evident in patient groups. It was also found that when compared with the normal group, the subjects in the depression group perceived the positive items as less positive. On the basis of present results, it is suggested that depressed subjects judged the emotional information with criteria different from normal individuals, and patients' emotional memory intensity is attenuated by their mood.
Commercial radioimmunoassay for beta subunit of human chorionic gonadotropin: falsely positive determinations due to elevated serum luteinizing hormone

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fowler, J.E. Jr.; Platoff, G.E.; Kubrock, C.A.

1982-01-01

Among 17 men who had received seemingly curative treatment for unilateral non-seminomatous germ cell tumors for the testis and who had consistently normal serum human chorionic gonadotropin (HCG) levels at a reference laboratory, 7 (41%) had at least one falsely positive commercial serum HCG determination. To investigate the cause of these falsely positive determinations the authors measured the cross reactivity of luteinizing hormone (LH) and follicle stimulating hormone (FSH) standards in the commercial HCG assay, and studied the relationships between commercial HCG levels and serum LH levels, serum FSH levels and gonadal status in men with and without normal gonadalmore » function. The falsely positive HCG determinations appeared to be due to elevated serum LH levels and cross reactivity of LH in the commercial HCG assay because: 1) there was substantial cross reactivity of the LH standards in the commercial assay, 2) the serum LH was elevated in four of six men with solitary testes, 3) there was a striking correlation between elevated serum LH levels and falsely elevated commercial HCG levels in ten men with solitary or absent testes, and 4) there were no falsely positive HCG determinations in 13 normal men but there were falsely positive HCG determinations in seven of ten anorchid men.« less
Trade-offs in Cervical Cancer Prevention: Balancing Benefits and Risks

PubMed Central

Stout, Natasha K.; Goldhaber-Fiebert, Jeremy D.; Ortendahl, Jesse D.; Goldie, Sue J.

2009-01-01

Background New screening and vaccination technologies will provide women with more options for cervical cancer prevention. Because the risk of cervical cancer diminishes with effective routine screening, women may wish to consider additional attributes, such as the likelihood of false-positive results and diagnostic procedures for mild abnormalities likely to resolve without intervention in their screening choices. Methods We used an empirically calibrated simulation model of cervical cancer in the United States to assess the benefits and potential risks associated with prevention strategies differing by primary screening test, triage test for abnormal results (cytologic testing, human papillomavirus [HPV] DNA test), and screening frequency. Outcomes included colposcopy referrals, cervical intraepithelial neoplasia (CIN) types 1 and 2 or 3, lifetime cancer risk, and quality-adjusted life expectancy. Results Across strategies, colposcopy referrals and diagnostic workups varied 3-fold, although diagnostic rates of CIN 2 or 3 were similar and 95% of positive screening test results were for mild abnormalities likely to resolve on their own. For a representative group of a thousand 20-year-old women undergoing triennial screening for 10 years, we expect 1038 colposcopy referrals (7 CIN 2 or 3 diagnoses) from combined cytologic and HPV DNA testing and fewer than 200 referrals (6–7 CIN 2 or 3 diagnoses) for strategies that use triage testing. Similarly, for a thousand 40-year-old women, combined cytologic and HPV DNA testing led to 489 referrals (9 CIN 2 or 3), whereas alternative strategies resulted in fewer than 150 referrals (7–8 CIN 2 or 3). Using cytologic testing followed by triage testing in younger women minimizes both diagnostic workups and positive HPV test results, whereas in older women diagnostic workups are minimized with HPV DNA testing followed by cytologic triage testing. Conclusions Clinically relevant information highlighting trade-offs among cervical cancer prevention strategies allows for inclusion of personal preferences into women’s decision making about screening and provides additional dimensions to the construction of clinical guidelines. PMID:18809815
Breast cancer detection risk in screening mammography after a false-positive result.

PubMed

Castells, X; Román, M; Romero, A; Blanch, J; Zubizarreta, R; Ascunce, N; Salas, D; Burón, A; Sala, M

2013-02-01

False-positives are a major concern in breast cancer screening. However, false-positives have been little evaluated as a prognostic factor for cancer detection. Our aim was to evaluate the association of false-positive results with the cancer detection risk in subsequent screening participations over a 17-year period. This is a retrospective cohort study of 762,506 women aged 45-69 years, with at least two screening participations, who underwent 2,594,146 screening mammograms from 1990 to 2006. Multilevel discrete-time hazard models were used to estimate the adjusted odds ratios (OR) of breast cancer detection in subsequent screening participations in women with false-positive results. False-positives involving a fine-needle aspiration cytology or a biopsy had a higher cancer detection risk than those involving additional imaging procedures alone (OR = 2.69; 95%CI: 2.28-3.16 and OR = 1.81; 95%CI: 1.70-1.94, respectively). The risk of cancer detection increased substantially if women with cytology or biopsy had a familial history of breast cancer (OR = 4.64; 95%CI: 3.23-6.66). Other factors associated with an increased cancer detection risk were age 65-69 years (OR = 1.84; 95%CI: 1.67-2.03), non-attendance at the previous screening invitation (OR = 1.26; 95%CI: 1.11-1.43), and having undergone a previous benign biopsy outside the screening program (OR = 1.24; 95%CI: 1.13-1.35). Women with a false-positive test have an increased risk of cancer detection in subsequent screening participations, especially those with a false-positive result involving cytology or biopsy. Understanding the factors behind this association could provide valuable information to increase the effectiveness of breast cancer screening. Copyright © 2012 Elsevier Ltd. All rights reserved.
Psychological distress in U.S. women who have experienced false-positive mammograms.

PubMed

Jatoi, Ismail; Zhu, Kangmin; Shah, Mona; Lawrence, William

2006-11-01

In the United States, approximately 10.7% of all screening mammograms lead to a false-positive result, but the overall impact of false-positives on psychological well-being is poorly understood. Data were analyzed from the 2000 U.S. National Health Interview Survey (NHIS), the most recent national survey that included a cancer control module. Study subjects were 9,755 women who ever had a mammogram, of which 1,450 had experienced a false-positive result. Psychological distress was assessed using the validated K6 questionnaire and logistic regression was used to discern any association with previous false-positive mammograms. In a multivariate analysis, women who had indicated a previous false-positive mammogram were more likely to report feeling sad (OR = 1.18, 95% CI, 1.03-1.35), restless (OR = 1.23, 95% CI, 1.08-1.40), worthless (OR = 1.27, 95% CI, 1.04-1.54), and finding that everything was an effort (OR = 1.27, 95% CI, 1.10-1.47). These women were also more likely to have seen a mental health professional in the 12 months preceding the survey (OR = 1.28, 95% CI, 1.03-1.58) and had a higher composite score on all items of the K6 scale (P < 0.0001), a reflection of increased psychological distress. Analyses by age and race revealed that, among women who had experienced false-positives, younger women were more likely to feel that everything was an effort, and blacks were more likely to feel restless. In a random sampling of the U.S. population, women who had previously experienced false-positive mammograms were more likely to report symptoms of anxiety and depression.
Evaluation of Natural Language Processing (NLP) Systems to Annotate Drug Product Labeling with MedDRA Terminology.

PubMed

Ly, Thomas; Pamer, Carol; Dang, Oanh; Brajovic, Sonja; Haider, Shahrukh; Botsis, Taxiarchis; Milward, David; Winter, Andrew; Lu, Susan; Ball, Robert

2018-05-31

The FDA Adverse Event Reporting System (FAERS) is a primary data source for identifying unlabeled adverse events (AEs) in a drug or biologic drug product's postmarketing phase. Many AE reports must be reviewed by drug safety experts to identify unlabeled AEs, even if the reported AEs are previously identified, labeled AEs. Integrating the labeling status of drug product AEs into FAERS could increase report triage and review efficiency. Medical Dictionary for Regulatory Activities (MedDRA) is the standard for coding AE terms in FAERS cases. However, drug manufacturers are not required to use MedDRA to describe AEs in product labels. We hypothesized that natural language processing (NLP) tools could assist in automating the extraction and MedDRA mapping of AE terms in drug product labels. We evaluated the performance of three NLP systems, (ETHER, I2E, MetaMap) for their ability to extract AE terms from drug labels and translate the terms to MedDRA Preferred Terms (PTs). Pharmacovigilance-based annotation guidelines for extracting AE terms from drug labels were developed for this study. We compared each system's output to MedDRA PT AE lists, manually mapped by FDA pharmacovigilance experts using the guidelines, for ten drug product labels known as the "gold standard AE list" (GSL) dataset. Strict time and configuration conditions were imposed in order to test each system's capabilities under conditions of no human intervention and minimal system configuration. Each NLP system's output was evaluated for precision, recall and F measure in comparison to the GSL. A qualitative error analysis (QEA) was conducted to categorize a random sample of each NLP system's false positive and false negative errors. A total of 417, 278, and 250 false positive errors occurred in the ETHER, I2E, and MetaMap outputs, respectively. A total of 100, 80, and 187 false negative errors occurred in ETHER, I2E, and MetaMap outputs, respectively. Precision ranged from 64% to 77%, recall from 64% to 83% and F measure from 67% to 79%. I2E had the highest precision (77%), recall (83%) and F measure (79%). ETHER had the lowest precision (64%). MetaMap had the lowest recall (64%). The QEA found that the most prevalent false positive errors were context errors such as "Context error/General term", "Context error/Instructions or monitoring parameters", "Context error/Medical history preexisting condition underlying condition risk factor or contraindication", and "Context error/AE manifestations or secondary complication". The most prevalent false negative errors were in the "Incomplete or missed extraction" error category. Missing AE terms were typically due to long terms, or terms containing non-contiguous words which do not correspond exactly to MedDRA synonyms. MedDRA mapping errors were a minority of errors for ETHER and I2E but were the most prevalent false positive errors for MetaMap. The results demonstrate that it may be feasible to use NLP tools to extract and map AE terms to MedDRA PTs. However, the NLP tools we tested would need to be modified or reconfigured to lower the error rates to support their use in a regulatory setting. Tools specific for extracting AE terms from drug labels and mapping the terms to MedDRA PTs may need to be developed to support pharmacovigilance. Conducting research using additional NLP systems on a larger, diverse GSL would also be informative. Copyright © 2018. Published by Elsevier Inc.
False Positive Probabilities for all Kepler Objects of Interest: 1284 Newly Validated Planets and 428 Likely False Positives

NASA Astrophysics Data System (ADS)

Morton, Timothy D.; Bryson, Stephen T.; Coughlin, Jeffrey L.; Rowe, Jason F.; Ravichandran, Ganesh; Petigura, Erik A.; Haas, Michael R.; Batalha, Natalie M.

2016-05-01

We present astrophysical false positive probability calculations for every Kepler Object of Interest (KOI)—the first large-scale demonstration of a fully automated transiting planet validation procedure. Out of 7056 KOIs, we determine that 1935 have probabilities <1% of being astrophysical false positives, and thus may be considered validated planets. Of these, 1284 have not yet been validated or confirmed by other methods. In addition, we identify 428 KOIs that are likely to be false positives, but have not yet been identified as such, though some of these may be a result of unidentified transit timing variations. A side product of these calculations is full stellar property posterior samplings for every host star, modeled as single, binary, and triple systems. These calculations use vespa, a publicly available Python package that is able to be easily applied to any transiting exoplanet candidate.
How to limit false positives in environmental DNA and metabarcoding?

PubMed

Ficetola, Gentile Francesco; Taberlet, Pierre; Coissac, Eric

2016-05-01

Environmental DNA (eDNA) and metabarcoding are boosting our ability to acquire data on species distribution in a variety of ecosystems. Nevertheless, as most of sampling approaches, eDNA is not perfect. It can fail to detect species that are actually present, and even false positives are possible: a species may be apparently detected in areas where it is actually absent. Controlling false positives remains a main challenge for eDNA analyses: in this issue of Molecular Ecology Resources, Lahoz-Monfort et al. () test the performance of multiple statistical modelling approaches to estimate the rate of detection and false positives from eDNA data. Here, we discuss the importance of controlling for false detection from early steps of eDNA analyses (laboratory, bioinformatics), to improve the quality of results and allow an efficient use of the site occupancy-detection modelling (SODM) framework for limiting false presences in eDNA analysis. © 2016 John Wiley & Sons Ltd.
Evaluation of MTANNs for eliminating false-positive with different computer aided pulmonary nodules detection software.

PubMed

Shi, Zhenghao; Ma, Jiejue; Feng, Yaning; He, Lifeng; Suzuki, Kenji

2015-11-01

MTANN (Massive Training Artificial Neural Network) is a promising tool, which applied to eliminate false-positive for thoracic CT in recent years. In order to evaluate whether this method is feasible to eliminate false-positive of different CAD schemes, especially, when it is applied to commercial CAD software, this paper evaluate the performance of the method for eliminating false-positives produced by three different versions of commercial CAD software for lung nodules detection in chest radiographs. Experimental results demonstrate that the approach is useful in reducing FPs for different computer aided lung nodules detection software in chest radiographs.
Computerized mass detection in whole breast ultrasound images: reduction of false positives using bilateral subtraction technique

NASA Astrophysics Data System (ADS)

Ikedo, Yuji; Fukuoka, Daisuke; Hara, Takeshi; Fujita, Hiroshi; Takada, Etsuo; Endo, Tokiko; Morita, Takako

2007-03-01

The comparison of left and right mammograms is a common technique used by radiologists for the detection and diagnosis of masses. In mammography, computer-aided detection (CAD) schemes using bilateral subtraction technique have been reported. However, in breast ultrasonography, there are no reports on CAD schemes using comparison of left and right breasts. In this study, we propose a scheme of false positive reduction based on bilateral subtraction technique in whole breast ultrasound images. Mass candidate regions are detected by using the information of edge directions. Bilateral breast images are registered with reference to the nipple positions and skin lines. A false positive region is detected based on a comparison of the average gray values of a mass candidate region and a region with the same position and same size as the candidate region in the contralateral breast. In evaluating the effectiveness of the false positive reduction method, three normal and three abnormal bilateral pairs of whole breast images were employed. These abnormal breasts included six masses larger than 5 mm in diameter. The sensitivity was 83% (5/6) with 13.8 (165/12) false positives per breast before applying the proposed reduction method. By applying the method, false positives were reduced to 4.5 (54/12) per breast without removing a true positive region. This preliminary study indicates that the bilateral subtraction technique is effective for improving the performance of a CAD scheme in whole breast ultrasound images.
Optimal False Discovery Rate Control for Dependent Data

PubMed Central

Xie, Jichun; Cai, T. Tony; Maris, John; Li, Hongzhe

2013-01-01

This paper considers the problem of optimal false discovery rate control when the test statistics are dependent. An optimal joint oracle procedure, which minimizes the false non-discovery rate subject to a constraint on the false discovery rate is developed. A data-driven marginal plug-in procedure is then proposed to approximate the optimal joint procedure for multivariate normal data. It is shown that the marginal procedure is asymptotically optimal for multivariate normal data with a short-range dependent covariance structure. Numerical results show that the marginal procedure controls false discovery rate and leads to a smaller false non-discovery rate than several commonly used p-value based false discovery rate controlling methods. The procedure is illustrated by an application to a genome-wide association study of neuroblastoma and it identifies a few more genetic variants that are potentially associated with neuroblastoma than several p-value-based false discovery rate controlling procedures. PMID:23378870
Evaluation of fecal elastase and serum cholecystokinin in dogs with a false positive fecal elastase test.

PubMed

Steiner, J M; Rehfeld, J F; Pantchev, N

2010-01-01

An assay for the measurement of pancreatic elastase in dog feces has been introduced. The goal of this study was to evaluate the rate of false-positive fecal-elastase test results in dogs with suspected exocrine pancreatic insufficiency (EPI) and to assess serum cholecystokinin (CCK) concentrations in dogs with a false positive fecal elastase test result. Twenty-six fecal and serum samples from dogs suspected of EPI, for which samples had been submitted to a commercial laboratory (Vet Med Labor) for analysis. Prospective study. Serum trypsin-like immunoreactivity (TLI) was measured in 26 dogs with a decreased fecal elastase concentration of <10 microg/g feces. Serum CCK concentrations were measured in 21 of these dogs. Of 26 dogs with a decreased fecal elastase concentration, 6 (23%) had serum TLI concentrations within or above the reference range. Serum CCK concentrations were significantly higher in dogs with a true positive fecal elastase test result (median: 1.1 pmol/L; range: 0.1-3.3 pmol/L) than in those with a false positive fecal elastase test result (median: 0.1 pmol/L; range: 0.1-0.9 pmol/L; P value = .0163). The rate of false positive fecal elastase test results was high in this group of dogs, suggesting that diagnosis of EPI must be confirmed by other means. The decreased CCK concentration in dogs with a false positive fecal elastase test result could suggest that false positive results are because of decreased stimulation of exocrine pancreatic function caused by other conditions.
Sherlock Holmes and child psychopathology assessment approaches: the case of the false-positive.

PubMed

Jensen, P S; Watanabe, H

1999-02-01

To explore the relative value of various methods of assessing childhood psychopathology, the authors compared 4 groups of children: those who met criteria for one or more DSM diagnoses and scored high on parent symptom checklists, those who met psychopathology criteria on either one of these two assessment approaches alone, and those who met no psychopathology assessment criterion. Parents of 201 children completed the Child Behavior Checklist (CBCL), after which children and parents were administered the Diagnostic Interview Schedule for Children (version 2.1). Children and parents also completed other survey measures and symptom report inventories. The 4 groups of children were compared against "external validators" to examine the merits of "false-positive" and "false-negative" cases. True-positive cases (those that met DSM criteria and scored high on the CBCL) differed significantly from the true-negative cases on most external validators. "False-positive" and "false-negative" cases had intermediate levels of most risk factors and external validators. "False-positive" cases were not normal per se because they scored significantly above the true-negative group on a number of risk factors and external validators. A similar but less marked pattern was noted for "false-negatives." Findings call into question whether cases with high symptom checklist scores despite no formal diagnoses should be considered "false-positive." Pending the availability of robust markers for mental illness, researchers and clinicians must resist the tendency to reify diagnostic categories or to engage in arcane debates about the superiority of one assessment approach over another.
Retrospective imaging study on the diagnosis of pathological false positive iodine-131 scans in patients with thyroid cancer.

PubMed

Jia, Qiang; Meng, Zhaowei; Tan, Jian; Zhang, Guizhi; He, Yajing; Sun, Haoran; Yu, Chunshui; Li, Dong; Zheng, Wei; Wang, Renfei; Wang, Shen; Li, Xue; Zhang, Jianping; Hu, Tianpeng; Liu, N A; Upadhyaya, Arun

2015-11-01

Iodine-131 (I-131) therapy and post-therapy I-131 scanning are essential in the management of differentiated thyroid cancer (DTC). However, pathological false positive I-131 scans can lead to misdiagnosis and inappropriate I-131 treatment. This retrospective study aimed to investigate the best imaging modality for the diagnosis of pathological false positive I-131 scans in a DTC patient cohort, and to determine its incidence. DTC patient data archived from January 2008 to January 2010 was retrieved. Post-therapeutic I-131 scans were conducted and interpreted. The imaging modalities of magnetic resonance imaging (MRI), computed tomography and ultrasonography were applied and compared to check all suspected lesions. Biopsy or needle aspiration was conducted for patients who consented to the acquisition of histopathological confirmation. Data for 156 DTC patients were retrieved. Only 6 cases of pathological false-positives were found among these (incidence, 3.85%), which included 3 cases of thymic hyperplasia in the mediastinum, 1 case of pleomorphic adenoma in the parapharyngeal space and 1 case of thyroglossal duct cyst in the neck. MRI was demonstrated as the best imaging modality for diagnosis due to its superior soft tissue resolution. However, no imaging modality was able to identify the abdominal false positive-lesions observed in 2 cases, one of whom also had thymic hyperplasia. In conclusion, pathological false positive I-131 scans occurred with an incidence of 3.85%. MRI was the best imaging modality for diagnosing these pathological false-positives.
Variation in false-positive rates of mammography reading among 1067 radiologists: a population-based assessment.

PubMed

Tan, Alai; Freeman, Daniel H; Goodwin, James S; Freeman, Jean L

2006-12-01

The accuracy of mammography reading varies among radiologists. We conducted a population-based assessment on radiologist variation in false- positive rates of screening mammography and its associated radiologist characteristics. About 27,394 screening mammograms interpreted by 1067 radiologists were identified from a 5% non-cancer sample of Medicare claims during 1998-1999. The data were linked to the American Medical Association Masterfile to obtain radiologist characteristics. Multilevel logistic regression models were used to examine the radiologist variation in false-positive rates of screening mammography and the associated radiologist characteristics. Radiologists varied substantially in the false-positive rates of screening mammography (ranging from 1.5 to 24.1%, adjusting for patient characteristics). A longer time period since graduation is associated with lower false-positive rates (odds ratio [OR] for every 10 years increase: 0.87, 95% Confidence Interval [CI], 0.81-0.94) and female radiologists had higher false-positive rates than male radiologists (OR = 1.25, 95% CI, 1.05-1.49), adjusting for patient and other radiologist characteristics. The unmeasured factors contributed to about 90% of the between-radiologist variance. Radiologists varied greatly in accuracy of mammography reading. Female and more recently trained radiologists had higher false-positive rates. The variation among radiologists was largely due to unmeasured factors, especially unmeasured radiologist factors. If our results are confirmed in further studies, they suggest that system-level interventions would be required to reduce variation in mammography interpretation.

Is it time to sound an alarm about false-positive cell-free DNA testing for fetal aneuploidy?

PubMed

Mennuti, Michael T; Cherry, Athena M; Morrissette, Jennifer J D; Dugoff, Lorraine

2013-11-01

Testing cell-free DNA (cfDNA) in maternal blood samples has been shown to have very high sensitivity for the detection of fetal aneuploidy with very low false-positive results in high-risk patients who undergo invasive prenatal diagnosis. Recent observation in clinical practice of several cases of positive cfDNA tests for trisomy 18 and trisomy 13, which were not confirmed by cytogenetic testing of the pregnancy, may reflect a limitation of the positive predictive value of this quantitative testing, particularly when it is used to detect rare aneuploidies. Analysis of a larger number of false-positive cases is needed to evaluate whether these observations reflect the positive predictive value that should be expected. Infrequently, mechanisms (such as low percentage mosaicism or confined placental mosaicism) might also lead to positive cfDNA testing that is not concordant with standard prenatal cytogenetic diagnosis. The need to explore these and other possible causes of false-positive cfDNA testing is exemplified by 2 of these cases. Additional evaluation of cfDNA testing in clinical practice and a mechanism for the systematic reporting of false-positive and false-negative cases will be important before this test is offered widely to the general population of low-risk obstetric patients. In the meantime, incorporating information about the positive predictive value in pretest counseling and in clinical laboratory reports is recommended. These experiences reinforce the importance of offering invasive testing to confirm cfDNA results before parental decision-making. Copyright © 2013 Mosby, Inc. All rights reserved.
Development of the 7-Item Binge-Eating Disorder Screener (BEDS-7)

PubMed Central

Deal, Linda S.; DiBenedetti, Dana B.; Nelson, Lauren; Fehnel, Sheri E.; Brown, T. Michelle

2016-01-01

Objective Develop a brief, patient-reported screening tool designed to identify individuals with probable binge-eating disorder (BED) for further evaluation or referral to specialists. Methods Items were developed on the basis of the DSM-5 diagnostic criteria, existing tools, and input from 3 clinical experts (January 2014). Items were then refined in cognitive debriefing interviews with participants self-reporting BED characteristics (March 2014) and piloted in a multisite, cross-sectional, prospective, noninterventional study consisting of a semistructured diagnostic interview (to diagnose BED) and administration of the pilot Binge-Eating Disorder Screener (BEDS), Binge Eating Scale (BES), and RAND 36-Item Short-Form Health Survey (RAND-36) (June 2014–July 2014). The sensitivity and specificity of classification algorithms (formed from the pilot BEDS item-level responses) in predicting BED diagnosis were evaluated. The final algorithm was selected to minimize false negatives and false positives, while utilizing the fewest number of BEDS items. Results Starting with the initial BEDS item pool (20 items), the 13-item pilot BEDS resulted from the cognitive debriefing interviews (n = 13). Of the 97 participants in the noninterventional study, 16 were diagnosed with BED (10/62 female, 16%; 6/35 male, 17%). Seven BEDS items (BEDS-7) yielded 100% sensitivity and 38.7% specificity. Participants correctly identified (true positives) had poorer BES scores and RAND-36 scores than participants identified as true negatives. Conclusions Implementation of the brief, patient-reported BEDS-7 in real-world clinical practice is expected to promote better understanding of BED characteristics and help physicians identify patients who may have BED. PMID:27486542
Development of the 7-Item Binge-Eating Disorder Screener (BEDS-7).

PubMed

Herman, Barry K; Deal, Linda S; DiBenedetti, Dana B; Nelson, Lauren; Fehnel, Sheri E; Brown, T Michelle

2016-01-01

Develop a brief, patient-reported screening tool designed to identify individuals with probable binge-eating disorder (BED) for further evaluation or referral to specialists. Items were developed on the basis of the DSM-5 diagnostic criteria, existing tools, and input from 3 clinical experts (January 2014). Items were then refined in cognitive debriefing interviews with participants self-reporting BED characteristics (March 2014) and piloted in a multisite, cross-sectional, prospective, noninterventional study consisting of a semistructured diagnostic interview (to diagnose BED) and administration of the pilot Binge-Eating Disorder Screener (BEDS), Binge Eating Scale (BES), and RAND 36-Item Short-Form Health Survey (RAND-36) (June 2014-July 2014). The sensitivity and specificity of classification algorithms (formed from the pilot BEDS item-level responses) in predicting BED diagnosis were evaluated. The final algorithm was selected to minimize false negatives and false positives, while utilizing the fewest number of BEDS items. Starting with the initial BEDS item pool (20 items), the 13-item pilot BEDS resulted from the cognitive debriefing interviews (n = 13). Of the 97 participants in the noninterventional study, 16 were diagnosed with BED (10/62 female, 16%; 6/35 male, 17%). Seven BEDS items (BEDS-7) yielded 100% sensitivity and 38.7% specificity. Participants correctly identified (true positives) had poorer BES scores and RAND-36 scores than participants identified as true negatives. Implementation of the brief, patient-reported BEDS-7 in real-world clinical practice is expected to promote better understanding of BED characteristics and help physicians identify patients who may have BED.
The Lancet Weight Determines Wheal Diameter in Response to Skin Prick Testing with Histamine.

PubMed

Andersen, Hjalte H; Lundgaard, Anna Charlotte; Petersen, Anne S; Hauberg, Lise E; Sharma, Neha; Hansen, Sofie D; Elberling, Jesper; Arendt-Nielsen, Lars

2016-01-01

Skin prick test (SPT) is a common test for diagnosing immunoglobulin E-mediated allergies. In clinical routine, technicalities, human errors or patient-related biases, occasionally results in suboptimal diagnosis of sensitization. Although not previously assessed qualitatively, lancet weight is hypothesized to be important when performing SPT to minimize the frequency of false positives, false negatives, and unwanted discomfort. Accurate weight-controlled SPT was performed on the volar forearms and backs of 20 healthy subjects. Four predetermined lancet weights were applied (25 g, 85 g, 135 g and 265 g) using two positive control histamine solutions (1 mg/mL and 10 mg/mL) and one negative control (saline). A total of 400 SPTs were conducted. The outcome parameters were: wheal size, neurogenic inflammation (measured by superficial blood perfusion), frequency of bleeding, and the lancet provoked pain response. The mean wheal diameter increased significantly as higher weights were applied to the SPT lancet, e.g. from 3.2 ± 0.28 mm at 25 g to 5.4 ± 1.7 mm at 265 g (p<0.01). Similarly, the frequency of bleeding, the provoked pain, and the neurogenic inflammatory response increased significantly. At 265 g saline evoked two wheal responses (/160 pricks) below 3 mm. The applied weight of the lancet during the SPT-procedure is an important factor. Higher lancet weights precipitate significantly larger wheal reactions with potential diagnostic implications. This warrants additional research of the optimal lancet weight in relation to SPT-guidelines to improve the specificity and sensitivity of the procedure.
The Lancet Weight Determines Wheal Diameter in Response to Skin Prick Testing with Histamine

PubMed Central

Andersen, Hjalte H.; Elberling, Jesper; Arendt-Nielsen, Lars

2016-01-01

Background Skin prick test (SPT) is a common test for diagnosing immunoglobulin E-mediated allergies. In clinical routine, technicalities, human errors or patient-related biases, occasionally results in suboptimal diagnosis of sensitization. Objective Although not previously assessed qualitatively, lancet weight is hypothesized to be important when performing SPT to minimize the frequency of false positives, false negatives, and unwanted discomfort. Methods Accurate weight-controlled SPT was performed on the volar forearms and backs of 20 healthy subjects. Four predetermined lancet weights were applied (25 g, 85 g, 135 g and 265 g) using two positive control histamine solutions (1 mg/mL and 10 mg/mL) and one negative control (saline). A total of 400 SPTs were conducted. The outcome parameters were: wheal size, neurogenic inflammation (measured by superficial blood perfusion), frequency of bleeding, and the lancet provoked pain response. Results The mean wheal diameter increased significantly as higher weights were applied to the SPT lancet, e.g. from 3.2 ± 0.28 mm at 25 g to 5.4 ± 1.7 mm at 265 g (p<0.01). Similarly, the frequency of bleeding, the provoked pain, and the neurogenic inflammatory response increased significantly. At 265 g saline evoked two wheal responses (/160 pricks) below 3 mm. Conclusion and clinical relevance The applied weight of the lancet during the SPT-procedure is an important factor. Higher lancet weights precipitate significantly larger wheal reactions with potential diagnostic implications. This warrants additional research of the optimal lancet weight in relation to SPT-guidelines to improve the specificity and sensitivity of the procedure. PMID:27213613
Ubiquitinated Proteome: Ready for Global?*

PubMed Central

Shi, Yi; Xu, Ping; Qin, Jun

2011-01-01

Ubiquitin (Ub) is a small and highly conserved protein that can covalently modify protein substrates. Ubiquitination is one of the major post-translational modifications that regulate a broad spectrum of cellular functions. The advancement of mass spectrometers as well as the development of new affinity purification tools has greatly expedited proteome-wide analysis of several post-translational modifications (e.g. phosphorylation, glycosylation, and acetylation). In contrast, large-scale profiling of lysine ubiquitination remains a challenge. Most recently, new Ub affinity reagents such as Ub remnant antibody and tandem Ub binding domains have been developed, allowing for relatively large-scale detection of several hundreds of lysine ubiquitination events in human cells. Here we review different strategies for the identification of ubiquitination site and discuss several issues associated with data analysis. We suggest that careful interpretation and orthogonal confirmation of MS spectra is necessary to minimize false positive assignments by automatic searching algorithms. PMID:21339389
Genome-wide assessment of differential translations with ribosome profiling data.

PubMed

Xiao, Zhengtao; Zou, Qin; Liu, Yu; Yang, Xuerui

2016-04-04

The closely regulated process of mRNA translation is crucial for precise control of protein abundance and quality. Ribosome profiling, a combination of ribosome foot-printing and RNA deep sequencing, has been used in a large variety of studies to quantify genome-wide mRNA translation. Here, we developed Xtail, an analysis pipeline tailored for ribosome profiling data that comprehensively and accurately identifies differentially translated genes in pairwise comparisons. Applied on simulated and real datasets, Xtail exhibits high sensitivity with minimal false-positive rates, outperforming existing methods in the accuracy of quantifying differential translations. With published ribosome profiling datasets, Xtail does not only reveal differentially translated genes that make biological sense, but also uncovers new events of differential translation in human cancer cells on mTOR signalling perturbation and in human primary macrophages on interferon gamma (IFN-γ) treatment. This demonstrates the value of Xtail in providing novel insights into the molecular mechanisms that involve translational dysregulations.
Multi-criteria decision making approaches for quality control of genome-wide association studies.

PubMed

Malovini, Alberto; Rognoni, Carla; Puca, Annibale; Bellazzi, Riccardo

2009-03-01

Experimental errors in the genotyping phases of a Genome-Wide Association Study (GWAS) can lead to false positive findings and to spurious associations. An appropriate quality control phase could minimize the effects of this kind of errors. Several filtering criteria can be used to perform quality control. Currently, no formal methods have been proposed for taking into account at the same time these criteria and the experimenter's preferences. In this paper we propose two strategies for setting appropriate genotyping rate thresholds for GWAS quality control. These two approaches are based on the Multi-Criteria Decision Making theory. We have applied our method on a real dataset composed by 734 individuals affected by Arterial Hypertension (AH) and 486 nonagenarians without history of AH. The proposed strategies appear to deal with GWAS quality control in a sound way, as they lead to rationalize and make explicit the experimenter's choices thus providing more reproducible results.
Logical Differential Prediction Bayes Net, improving breast cancer diagnosis for older women.

PubMed

Nassif, Houssam; Wu, Yirong; Page, David; Burnside, Elizabeth

2012-01-01

Overdiagnosis is a phenomenon in which screening identities cancer which may not go on to cause symptoms or death. Women over 65 who develop breast cancer bear the heaviest burden of overdiagnosis. This work introduces novel machine learning algorithms to improve diagnostic accuracy of breast cancer in aging populations. At the same time, we aim at minimizing unnecessary invasive procedures (thus decreasing false positives) and concomitantly addressing overdiagnosis. We develop a novel algorithm. Logical Differential Prediction Bayes Net (LDP-BN), that calculates the risk of breast disease based on mammography findings. LDP-BN uses Inductive Logic Programming (ILP) to learn relational rules, selects older-specific differentially predictive rules, and incorporates them into a Bayes Net, significantly improving its performance. In addition, LDP-BN offers valuable insight into the classification process, revealing novel older-specific rules that link mass presence to invasive, and calcification presence and lack of detectable mass to DCIS.
False-positive findings in Cochrane meta-analyses with and without application of trial sequential analysis: an empirical review.

PubMed

Imberger, Georgina; Thorlund, Kristian; Gluud, Christian; Wetterslev, Jørn

2016-08-12

Many published meta-analyses are underpowered. We explored the role of trial sequential analysis (TSA) in assessing the reliability of conclusions in underpowered meta-analyses. We screened The Cochrane Database of Systematic Reviews and selected 100 meta-analyses with a binary outcome, a negative result and sufficient power. We defined a negative result as one where the 95% CI for the effect included 1.00, a positive result as one where the 95% CI did not include 1.00, and sufficient power as the required information size for 80% power, 5% type 1 error, relative risk reduction of 10% or number needed to treat of 100, and control event proportion and heterogeneity taken from the included studies. We re-conducted the meta-analyses, using conventional cumulative techniques, to measure how many false positives would have occurred if these meta-analyses had been updated after each new trial. For each false positive, we performed TSA, using three different approaches. We screened 4736 systematic reviews to find 100 meta-analyses that fulfilled our inclusion criteria. Using conventional cumulative meta-analysis, false positives were present in seven of the meta-analyses (7%, 95% CI 3% to 14%), occurring more than once in three. The total number of false positives was 14 and TSA prevented 13 of these (93%, 95% CI 68% to 98%). In a post hoc analysis, we found that Cochrane meta-analyses that are negative are 1.67 times more likely to be updated (95% CI 0.92 to 2.68) than those that are positive. We found false positives in 7% (95% CI 3% to 14%) of the included meta-analyses. Owing to limitations of external validity and to the decreased likelihood of updating positive meta-analyses, the true proportion of false positives in meta-analysis is probably higher. TSA prevented 93% of the false positives (95% CI 68% to 98%). Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/
Working memory affects false memory production for emotional events.

PubMed

Mirandola, Chiara; Toffalini, Enrico; Ciriello, Alfonso; Cornoldi, Cesare

2017-01-01

Whereas a link between working memory (WM) and memory distortions has been demonstrated, its influence on emotional false memories is unclear. In two experiments, a verbal WM task and a false memory paradigm for negative, positive or neutral events were employed. In Experiment 1, we investigated individual differences in verbal WM and found that the interaction between valence and WM predicted false recognition, with negative and positive material protecting high WM individuals against false remembering; the beneficial effect of negative material disappeared in low WM participants. In Experiment 2, we lowered the WM capacity of half of the participants with a double task request, which led to an overall increase in false memories; furthermore, consistent with Experiment 1, the increase in negative false memories was larger than that of neutral or positive ones. It is concluded that WM plays a critical role in determining false memory production, specifically influencing the processing of negative material.
Detection of Biological Pathogens Using Multiple Wireless Magnetoelastic Biosensors

NASA Astrophysics Data System (ADS)

Shen, Wen

A number of recent, high-profile incidences of food-borne illness spreading through the food supply and the use of anthrax by terrorists after the September 11, 2001 attacks have demonstrated the need for new technologies that can rapidly detect the presence of biological pathogens. A bevy of biosensors show excellent detection sensitivity and specificity. However, false positive and false negative signals remain one of the primary reasons that many of these newly developed biosensors have not found application in the marketplace. The research described in this dissertation focuses on developing a free-standing magnetoelastic based bio-sensing system using a pulse method. This method allows fast detection, eliminates the bias magnetic field that is necessary in current methods, makes the system more simply and suitable for in-field detection. This system has two pairs of transformer coils, where a measurement sensor and a control sensor can be put in each pair of coils. The control sensor is used to compensate for environmental variables. The effect of pulse power on the performance of the magnetoelastic sensors in the pulse system is studied. The system is found to have excellent stability, good detection repeatability when used with multiple sensors. This research has investigated and demonstrated a multiple sensors approach. Because it will involve the simultaneous measurement of many sensors, it will significantly reduce problems encountered with false positive indications. The positioning and interference of sensors are investigated. By adding a multi-channel structure to the pulse detection system, the effect of sensor interference is minimized. The result of the repeatability test shows that the standard deviation when measuring three 1 mm magnetoelastic sensors is around 500 Hz, which is smaller than the minimum requirement for actual spores/bacteria detection. Magnetoelastic sensors immobilized with JRB7 phages and E2 phages have been used to specifically detect Bacillus anthracis spores and Salmonella typhimurium bacteria. The real-time monitoring of the detection of B. anthracis spores in a flowing system was performed using 2 mm sensors and 1 mm sensors. The detection of S. typhimurium in air has been performed using the pulse based system with both single and grouped sensors. Because grouped sensor detection involves the simultaneous measurement of many sensors, statistical evaluation shows that it can significantly reduce problems encountered with false positive indications. This method has been implemented in an investigation of a method that allows direct detection of S. typhimurium on cantaloupe surfaces. It has been demonstrated that multiple E2 phage based magnetoelastic sensors are able to detect Salmonella directly on fresh cantaloupe surfaces. Confirmation of the spore or bacteria binding to the sensor surfaces was achieved through SEM study of the sensor surfaces.
Automated matching of supine and prone colonic polyps based on PCA and SVMs

NASA Astrophysics Data System (ADS)

Wang, Shijun; Van Uitert, Robert L.; Summers, Ronald M.

2008-03-01

Computed tomographic colonography (CTC) is a feasible and minimally invasive method for the detection of colorectal polyps and cancer screening. In current practice, a patient will be scanned twice during the CTC examination - once supine and once prone. In order to assist the radiologists in evaluating colon polyp candidates in both scans, we expect the computer aided detection (CAD) system can provide not only the locations of suspicious polyps, but also the possible matched pairs of polyps in two scans. In this paper, we propose a new automated matching method based on the extracted features of polyps by using principal component analysis (PCA) and Support Vector Machines (SVMs). Our dataset comes from the 104 CT scans of 52 patients with supine and prone positions collected from three medical centers. From it we constructed two groups of matched polyp candidates according to the size of true polyps: group A contains 12 true polyp pairs (> 9 mm) and 454 false pairs; group B contains 24 true polyp pairs (6-9 mm) and 514 false pairs. By using PCA, we reduced the dimensions of original data (with 157 attributes) to 30 dimensions. We did leave-one-patient-out test on the two groups of data. ROC analysis shows that it is easier to match bigger polyps than that of smaller polyps. On group A data, when false alarm probability is 0.18, the sensitivity of SVM achieves 0.83 which shows that automated matching of polyp candidates is practicable for clinical applications.
Evaluation of positive and false-positive results in syphilis screening of blood donors in Rio de Janeiro, Brazil.

PubMed

Sandes, V S; Silva, S G C; Motta, I J F; Velarde, L G C; de Castilho, S R

2017-06-01

We propose to analyse the positive and false-positive results of treponemal and nontreponemal tests in blood donors from Brazil and to evaluate possible factors associated with the results of treponemal tests. Treponemal tests have been used widely for syphilis screening in blood banks. The introduction of these tests in donor screening has caused an impact and a loss of donors who need to be assessed. This was a retrospective cross-sectional study of syphilis screening and confirmatory test results of blood donors that were obtained before and after adopting a chemiluminescent immunoassay (CLIA). A comparative analysis was performed using a second sample drawn from positive donors. The possible factors associated with CLIA-positive or CLIA-false-positive results were investigated in a subgroup. Statistical tests were used to compare the proportions and adjusted estimates of association. The reactivity rate increased from 1·01% (N = 28 158) to 2·66% (N = 25 577) after introducing the new test. Among Venereal Disease Research Laboratory (VDRL)- and CLIA-confirmed results, the false-positive rates were 40·5% (N = 180) and 37·4% (N = 359), respectively (P = 0·5266). Older donors (OR = 1·04; P = 0·0010) and donors with lower education levels (OR = 6·59; P = 0·0029) were associated with a higher risk of positivity for syphilis. CLIA represents an improvement in blood bank serological screening. However, its use in a healthy population appears to result in high rates of false positives. Identifying which characteristics can predict false positives, however, remains a challenge. © 2017 British Blood Transfusion Society.
False-positive cryptococcal antigen latex agglutination caused by disinfectants and soaps.

PubMed Central

Blevins, L B; Fenn, J; Segal, H; Newcomb-Gayman, P; Carroll, K C

1995-01-01

Five disinfectants or soaps were tested to determine if any could be responsible for false-positive results obtained with the Latex-Crypto Antigen Detection System kit (Immuno-Mycologics, Inc., Norman, Okla.). Three disinfectants or soaps (Derma soap, 7X, and Bacdown) produced false-positive agglutination after repeated washing of ring slides during testing of a known negative cerebrospinal fluid specimen. PMID:7650214
How pH, Temperature, and Time of Incubation Affect False-Positive Responses and Uncertainty of the LAL Gel-Clot Test.

PubMed

Lourenço, Felipe Rebello; Botelho, Túlia De Souza; Pinto, Terezinha De Jesus Andreoli

2012-01-01

The limulus amebocyte lysate (LAL) test is the simplest and most widely used procedure for detection of endotoxin in parenteral drugs. The LAL test demands optimal pH, ionic strength, temperature, and time of incubation. Slight changes in these parameters may increase the frequency of false-positive responses and the estimated uncertainty of the LAL test. The aim of this paper is to evaluate how changes in the pH, temperature, and time of incubation affect the occurrence of false-positive responses in the LAL test. LAL tests were performed in nominal conditions (37 °C, 60 min, and pH 7) and in different conditions of temperature (36 °C and 38 °C), time of incubation (58 and 62 min), and pH (6 and 8). Slight differences in pH increase the frequency of false-positive responses 5-fold (relative risk 5.0), resulting in an estimated of uncertainty 7.6%. Temperature and time of incubation affect the LAL test less, showing relative risks of 1.5 and 1.0, respectively. Estimated uncertainties in 36 °C or 38 °C temperatures and 58 or 62 min of incubation were found to be 2.0% and 1.0%, respectively. Simultaneous differences in these parameters significantly increase the frequency of false-positive responses. The limulus amebocyte lysate (LAL) gel-clot test is a simple test for detection of endotoxin from Gram-negative bacteria. The test is based on a gel formation when a certain amount of endotoxin is present; it is a pass/fail test. The LAL test requires optimal pH, ionic strength, temperature, and time of incubation. Slight difference in these parameters may increase the frequency of false-positive responses. The aim of this paper is to evaluate how changes in the pH, temperature, and time of incubation affect the occurrence of false-positive responses in the LAL test. We find that slight differences in pH increase the frequency of false-positive responses 5-fold. Temperature and time of incubation affect the LAL test less. Simultaneous differences in these parameters significantly increase the frequency of false-positive responses.
Reducing false positives of microcalcification detection systems by removal of breast arterial calcifications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mordang, Jan-Jurre, E-mail: Jan-Jurre.Mordang@radboudumc.nl; Gubern-Mérida, Albert; Karssemeijer, Nico

Purpose: In the past decades, computer-aided detection (CADe) systems have been developed to aid screening radiologists in the detection of malignant microcalcifications. These systems are useful to avoid perceptual oversights and can increase the radiologists’ detection rate. However, due to the high number of false positives marked by these CADe systems, they are not yet suitable as an independent reader. Breast arterial calcifications (BACs) are one of the most frequent false positives marked by CADe systems. In this study, a method is proposed for the elimination of BACs as positive findings. Removal of these false positives will increase the performancemore » of the CADe system in finding malignant microcalcifications. Methods: A multistage method is proposed for the removal of BAC findings. The first stage consists of a microcalcification candidate selection, segmentation and grouping of the microcalcifications, and classification to remove obvious false positives. In the second stage, a case-based selection is applied where cases are selected which contain BACs. In the final stage, BACs are removed from the selected cases. The BACs removal stage consists of a GentleBoost classifier trained on microcalcification features describing their shape, topology, and texture. Additionally, novel features are introduced to discriminate BACs from other positive findings. Results: The CADe system was evaluated with and without BACs removal. Here, both systems were applied on a validation set containing 1088 cases of which 95 cases contained malignant microcalcifications. After bootstrapping, free-response receiver operating characteristics and receiver operating characteristics analyses were carried out. Performance between the two systems was compared at 0.98 and 0.95 specificity. At a specificity of 0.98, the sensitivity increased from 37% to 52% and the sensitivity increased from 62% up to 76% at a specificity of 0.95. Partial areas under the curve in the specificity range of 0.8–1.0 were significantly different between the system without BACs removal and the system with BACs removal, 0.129 ± 0.009 versus 0.144 ± 0.008 (p<0.05), respectively. Additionally, the sensitivity at one false positive per 50 cases and one false positive per 25 cases increased as well, 37% versus 51% (p<0.05) and 58% versus 67% (p<0.05) sensitivity, respectively. Additionally, the CADe system with BACs removal reduces the number of false positives per case by 29% on average. The same sensitivity at one false positive per 50 cases in the CADe system without BACs removal can be achieved at one false positive per 80 cases in the CADe system with BACs removal. Conclusions: By using dedicated algorithms to detect and remove breast arterial calcifications, the performance of CADe systems can be improved, in particular, at false positive rates representative for operating points used in screening.« less
Bone marrow cells stained by azide-conjugated Alexa fluors in the absence of an alkyne label.

PubMed

Lin, Guiting; Ning, Hongxiu; Banie, Lia; Qiu, Xuefeng; Zhang, Haiyang; Lue, Tom F; Lin, Ching-Shwun

2012-09-01

Thymidine analog 5-ethynyl-2'-deoxyuridine (EdU) has recently been introduced as an alternative to 5-bromo-2-deoxyuridine (BrdU) for cell labeling and tracking. Incorporation of EdU into replicating DNA can be detected by azide-conjugated fluors (eg, Alexa-azide) through a Cu(i)-catalyzed click reaction between EdU's alkyne moiety and azide. While this cell labeling method has proven to be valuable for tracking transplanted stem cells in various tissues, we have found that some bone marrow cells could be stained by Alexa-azide in the absence of EdU label. In intact rat femoral bone marrow, ~3% of nucleated cells were false-positively stained, and in isolated bone marrow cells, ~13%. In contrast to true-positive stains, which localize in the nucleus, the false-positive stains were cytoplasmic. Furthermore, while true-positive staining requires Cu(i), false-positive staining does not. Reducing the click reaction time or reducing the Alexa-azide concentration failed to improve the distinction between true- and false-positive staining. Hematopoietic and mesenchymal stem cell markers CD34 and Stro-1 did not co-localize with the false-positively stained cells, and these cells' identity remains unknown.
Utility of Intraoperative Neuromonitoring during Minimally Invasive Fusion of the Sacroiliac Joint.

PubMed

Woods, Michael; Birkholz, Denise; MacBarb, Regina; Capobianco, Robyn; Woods, Adam

2014-01-01

Study Design. Retrospective case series. Objective. To document the clinical utility of intraoperative neuromonitoring during minimally invasive surgical sacroiliac joint fusion for patients diagnosed with sacroiliac joint dysfunction (as a direct result of sacroiliac joint disruptions or degenerative sacroiliitis) and determine stimulated electromyography thresholds reflective of favorable implant position. Summary of Background Data. Intraoperative neuromonitoring is a well-accepted adjunct to minimally invasive pedicle screw placement. The utility of intraoperative neuromonitoring during minimally invasive surgical sacroiliac joint fusion using a series of triangular, titanium porous plasma coated implants has not been evaluated. Methods. A medical chart review of consecutive patients treated with minimally invasive surgical sacroiliac joint fusion was undertaken at a single center. Baseline patient demographics and medical history, intraoperative electromyography thresholds, and perioperative adverse events were collected after obtaining IRB approval. Results. 111 implants were placed in 37 patients. Sensitivity of EMG was 80% and specificity was 97%. Intraoperative neuromonitoring potentially avoided neurologic sequelae as a result of improper positioning in 7% of implants. Conclusions. The results of this study suggest that intraoperative neuromonitoring may be a useful adjunct to minimally invasive surgical sacroiliac joint fusion in avoiding nerve injury during implant placement.
Empirical analysis on future-cash arbitrage risk with portfolio VaR

NASA Astrophysics Data System (ADS)

Chen, Rongda; Li, Cong; Wang, Weijin; Wang, Ze

2014-03-01

This paper constructs the positive arbitrage position by alternating the spot index with Chinese Exchange Traded Fund (ETF) portfolio and estimating the arbitrage-free interval of futures with the latest trade data. Then, an improved Delta-normal method was used, which replaces the simple linear correlation coefficient with tail dependence correlation coefficient, to measure VaR (Value-at-risk) of the arbitrage position. Analysis of VaR implies that the risk of future-cash arbitrage is less than that of investing completely in either futures or spot market. Then according to the compositional VaR and the marginal VaR, we should increase the futures position and decrease the spot position appropriately to minimize the VaR, which can minimize risk subject to certain revenues.

The Illusion of the Positive: The impact of natural and induced mood on older adults’ false recall

PubMed Central

Emery, Lisa; Hess, Thomas M.; Elliot, Tonya

2012-01-01

Recent research suggests that affective and motivational processes can influence age differences in memory. In the current study, we examine the impact of both natural and induced mood state on age differences in false recall. Older and younger adults performed a version of the Deese-Roediger-McDermott (DRM; Roediger & McDermott, 1995) false memory paradigm in either their natural mood state or after a positive or negative mood induction. Results indicated that, after accounting for age differences in basic cognitive function, age-related differences in positive mood during the testing session were related to increased false recall in older adults. Inducing older adults into a positive mood also exacerbated age differences in false memory. In contrast, veridical recall did not appear to be systematically influenced by mood. Together, these results suggest that positive mood states can impact older adults’ information processing and potentially increase underlying cognitive age differences. PMID:22292431
The illusion of the positive: the impact of natural and induced mood on older adults' false recall.

PubMed

Emery, Lisa; Hess, Thomas M; Elliot, Tonya

2012-11-01

Recent research suggests that affective and motivational processes can influence age differences in memory. In the current study, we examine the impact of both natural and induced mood state on age differences in false recall. Older and younger adults performed a version of the Deese-Roediger-McDermott (DRM; Roediger & McDermott, 1995 , Journal of Experimental Psychology: Learning, Memory, and Cognition, 21, 803) false memory paradigm in either their natural mood state or after a positive or negative mood induction. Results indicated that, after accounting for age differences in basic cognitive function, age-related differences in positive mood during the testing session were related to increased false recall in older adults. Inducing older adults into a positive mood also exacerbated age differences in false memory. In contrast, veridical recall did not appear to be systematically influenced by mood. Together, these results suggest that positive mood states can impact older adults' information processing and potentially increase underlying cognitive age differences.
Search for Minimal and Semi-Minimal Rule Sets in Incremental Learning of Context-Free and Definite Clause Grammars

NASA Astrophysics Data System (ADS)

Imada, Keita; Nakamura, Katsuhiko

This paper describes recent improvements to Synapse system for incremental learning of general context-free grammars (CFGs) and definite clause grammars (DCGs) from positive and negative sample strings. An important feature of our approach is incremental learning, which is realized by a rule generation mechanism called “bridging” based on bottom-up parsing for positive samples and the search for rule sets. The sizes of rule sets and the computation time depend on the search strategies. In addition to the global search for synthesizing minimal rule sets and serial search, another method for synthesizing semi-optimum rule sets, we incorporate beam search to the system for synthesizing semi-minimal rule sets. The paper shows several experimental results on learning CFGs and DCGs, and we analyze the sizes of rule sets and the computation time.
Evaluation of the Architect HIV Ag/Ab Combo Assay in a low-prevalence setting: The role of samples with a low S/CO ratio.

PubMed

Alonso, Roberto; Pérez-García, Felipe; Gijón, Paloma; Collazos, Ana; Bouza, Emilio

2018-06-01

The Architect HIV Ag/Ab Combo Assay, a fourth-generation ELISA, has proven to be highly reliable for the diagnosis of HIV infection. However, its high sensitivity may lead to false-positive results. To evaluate the diagnostic performance of Architect in a low-prevalence population and to assess the role of the sample-to-cutoff ratio (S/CO) in reducing the frequency of false-positive results. We conducted a retrospective study of samples analyzed by Architect between January 2015 and June 2017. Positive samples were confirmed by immunoblot (RIBA) or nucleic acid amplification tests (NAATs). Different S/CO thresholds (1, 2.5, 10, 25, and 100) were analyzed to determine sensitivity, specificity, and negative and positive predictive values (NPV, PPV). ROC analysis was used to determine the optimal S/CO. A total of 69,471 samples were analyzed. 709 (1.02%) were positive by Architect. Of these, 63 (8.89%) were false-positive results. Most of them (93.65%) were in samples with S/CO < 100. However, most confirmations by NAATs (12 out of 19 cases) were also recorded for these samples. The optimal S/CO was 2.5, which provided the highest area under the ROC curve (0.9998) and no false-negative results. With this S/CO, sensitivity and specificity were 100.0%, and PPV and NPV were 95.8% and 100.0%, respectively. In addition, the frequency of false-positive results decreased significantly to 4.15%. Although Architect generates a relatively high number of false-positive results, raising the S/CO limit too much to increase specificity can lead to false-negative results, especially in newly infected individuals. Copyright © 2018 Elsevier B.V. All rights reserved.
Prehospital Acute ST-Elevation Myocardial Infarction Identification in San Diego: A Retrospective Analysis of the Effect of a New Software Algorithm.

PubMed

Coffey, Christanne; Serra, John; Goebel, Mat; Espinoza, Sarah; Castillo, Edward; Dunford, James

2018-05-03

A significant increase in false positive ST-elevation myocardial infarction (STEMI) electrocardiogram interpretations was noted after replacement of all of the City of San Diego's 110 monitor-defibrillator units with a new brand. These concerns were brought to the manufacturer and a revised interpretive algorithm was implemented. This study evaluated the effects of a revised interpretation algorithm to identify STEMI when used by San Diego paramedics. Data were reviewed 6 months before and 6 months after the introduction of a revised interpretation algorithm. True-positive and false-positive interpretations were identified. Factors contributing to an incorrect interpretation were assessed and patient demographics were collected. A total of 372 (234 preimplementation, 138 postimplementation) cases met inclusion criteria. There was a significant reduction in false positive STEMI (150 preimplementation, 40 postimplementation; p < 0.001) after implementation. The most common factors resulting in false positive before implementation were right bundle branch block, left bundle branch block, and atrial fibrillation. The new algorithm corrected for these misinterpretations with most postimplementation false positives attributed to benign early repolarization and poor data quality. Subsequent follow-up at 10 months showed maintenance of the observed reduction in false positives. This study shows that introducing a revised 12-lead interpretive algorithm resulted in a significant reduction in the number of false positive STEMI electrocardiogram interpretations in a large urban emergency medical services system. Rigorous testing and standardization of new interpretative software is recommended before introduction into a clinical setting to prevent issues resulting from inappropriate cardiac catheterization laboratory activations. Copyright © 2018 Elsevier Inc. All rights reserved.
True detection limits in an experimental linearly heteroscedastic system.. Part 2

NASA Astrophysics Data System (ADS)

Voigtman, Edward; Abraham, Kevin T.

2011-11-01

Despite much different processing of the experimental fluorescence detection data presented in Part 1, essentially the same estimates were obtained for the true theoretical Currie decision levels ( YC and XC) and true Currie detection limits ( YD and XD). The obtained experimental values, for 5% probability of false positives and 5% probability of false negatives, were YC = 56.0 mV, YD = 125. mV, XC = 0.132 μg/mL and XD = 0.293 μg/mL. For 5% probability of false positives and 1% probability of false negatives, the obtained detection limits were YD = 158 . mV and XD = 0.371 μg/mL. Furthermore, by using bootstrapping methodology on the experimental data for the standards and the analytical blank, it was possible to validate previously published experimental domain expressions for the decision levels ( yC and xC) and detection limits ( yD and xD). This was demonstrated by testing the generated decision levels and detection limits for their performance in regard to false positives and false negatives. In every case, the obtained numbers of false negatives and false positives were as specified a priori.
Interval Breast Cancer Rates and Histopathologic Tumor Characteristics after False-Positive Findings at Mammography in a Population-based Screening Program.

PubMed

Hofvind, Solveig; Sagstad, Silje; Sebuødegård, Sofie; Chen, Ying; Roman, Marta; Lee, Christoph I

2018-04-01

Purpose To compare rates and tumor characteristics of interval breast cancers (IBCs) detected after a negative versus false-positive screening among women participating in the Norwegian Breast Cancer Screening Program. Materials and Methods The Cancer Registry Regulation approved this retrospective study. Information about 423 445 women aged 49-71 years who underwent 789 481 full-field digital mammographic screening examinations during 2004-2012 was extracted from the Cancer Registry of Norway. Rates and odds ratios of IBC among women with a negative (the reference group) versus a false-positive screening were estimated by using logistic regression models adjusted for age at diagnosis and county of residence. Results A total of 1302 IBCs were diagnosed after 789 481 screening examinations, of which 7.0% (91 of 1302) were detected among women with a false-positive screening as the most recent breast imaging examination before detection. By using negative screening as the reference, adjusted odds ratios of IBCs were 3.3 (95% confidence interval [CI]: 2.6, 4.2) and 2.8 (95% CI: 1.8, 4.4) for women with a false-positive screening without and with needle biopsy, respectively. Women with a previous negative screening had a significantly lower proportion of tumors that were 10 mm or less (14.3% [150 of 1049] vs 50.0% [seven of 14], respectively; P < .01) and grade I tumors (13.2% [147 of 1114] vs 42.9% [six of 14]; P < .01), but a higher proportion of cases with lymph nodes positive for cancer (40.9% [442 of 1080] vs 13.3% [two of 15], respectively; P = .03) compared with women with a previous false-positive screening with benign biopsy. A retrospective review of the screening mammographic examinations identified 42.9% (39 of 91) of the false-positive cases to be the same lesion as the IBC. Conclusion By using a negative screening as the reference, a false-positive screening examination increased the risk of an IBC three-fold. The tumor characteristics of IBC after a negative screening were less favorable compared with those detected after a previous false-positive screening. © RSNA, 2017 Online supplemental material is available for this article.
Annual Research Review: Positive adjustment to adversity -Trajectories of minimal-impact resilience and emergent resilience

PubMed Central

Bonanno, George A.; Diminich, Erica D.

2012-01-01

Background Research on resilience in the aftermath of potentially traumatic life events is still evolving. For decades researchers have documented resilience in children exposed to corrosive early environments, such as poverty or chronic maltreatment. Relatively more recently the study of resilience has migrated to the investigation of isolated and potentially traumatic life events (PTE) in adults. Methods In this article we first consider some of the key differences in the conceptualization of resilience following chronic adversity versus resilience following single-incident traumas, and then describe some of the misunderstandings that have developed about these constructs. To organize our discussion we introduce the terms emergent resilience and minimal-impact resilience to represent trajectories positive adjustment in these two domains, respectively. Results We focused in particular on minimal-impact resilience, and reviewed recent advances in statistical modeling of latent trajectories that have informed the most recent research on minimal-impact resilience in both children and adults and the variables that predict it, including demographic variables, exposure, past and current stressors, resources, personality, positive emotion, coping and appraisal, and flexibility in coping and emotion regulation. Conclusions The research on minimal impact resilience is nascent. Further research is warranted with implications for a multiple levels of analysis approach to elucidate the processes that may mitigate or modify the impact of a PTE at different developmental stages. PMID:23215790
Protein Charge and Mass Contribute to the Spatio-temporal Dynamics of Protein-Protein Interactions in a Minimal Proteome

PubMed Central

Xu, Yu; Wang, Hong; Nussinov, Ruth; Ma, Buyong

2013-01-01

We constructed and simulated a ‘minimal proteome’ model using Langevin dynamics. It contains 206 essential protein types which were compiled from the literature. For comparison, we generated six proteomes with randomized concentrations. We found that the net charges and molecular weights of the proteins in the minimal genome are not random. The net charge of a protein decreases linearly with molecular weight, with small proteins being mostly positively charged and large proteins negatively charged. The protein copy numbers in the minimal genome have the tendency to maximize the number of protein-protein interactions in the network. Negatively charged proteins which tend to have larger sizes can provide large collision cross-section allowing them to interact with other proteins; on the other hand, the smaller positively charged proteins could have higher diffusion speed and are more likely to collide with other proteins. Proteomes with random charge/mass populations form less stable clusters than those with experimental protein copy numbers. Our study suggests that ‘proper’ populations of negatively and positively charged proteins are important for maintaining a protein-protein interaction network in a proteome. It is interesting to note that the minimal genome model based on the charge and mass of E. Coli may have a larger protein-protein interaction network than that based on the lower organism M. pneumoniae. PMID:23420643
Gain-Scheduled Fault Tolerance Control Under False Identification

NASA Technical Reports Server (NTRS)

Shin, Jong-Yeob; Belcastro, Christine (Technical Monitor)

2006-01-01

An active fault tolerant control (FTC) law is generally sensitive to false identification since the control gain is reconfigured for fault occurrence. In the conventional FTC law design procedure, dynamic variations due to false identification are not considered. In this paper, an FTC synthesis method is developed in order to consider possible variations of closed-loop dynamics under false identification into the control design procedure. An active FTC synthesis problem is formulated into an LMI optimization problem to minimize the upper bound of the induced-L2 norm which can represent the worst-case performance degradation due to false identification. The developed synthesis method is applied for control of the longitudinal motions of FASER (Free-flying Airplane for Subscale Experimental Research). The designed FTC law of the airplane is simulated for pitch angle command tracking under a false identification case.
Minimal measures for Euler-Lagrange flows on finite covering spaces

NASA Astrophysics Data System (ADS)

Wang, Fang; Xia, Zhihong

2016-12-01

In this paper we study the minimal measures for positive definite Lagrangian systems on compact manifolds. We are particularly interested in manifolds with more complicated fundamental groups. Mather’s theory classifies the minimal or action-minimizing measures according to the first (co-)homology group of a given manifold. We extend Mather’s notion of minimal measures to a larger class for compact manifolds with non-commutative fundamental groups, and use finite coverings to study the structure of these extended minimal measures. We also define action-minimizers and minimal measures in the homotopical sense. Our program is to study the structure of homotopical minimal measures by considering Mather’s minimal measures on finite covering spaces. Our goal is to show that, in general, manifolds with a non-commutative fundamental group have a richer set of minimal measures, hence a richer dynamical structure. As an example, we study the geodesic flow on surfaces of higher genus. Indeed, by going to the finite covering spaces, the set of minimal measures is much larger and more interesting.
Anticipatory planning and control of grasp positions and forces for dexterous two-digit manipulation.

PubMed

Fu, Qiushi; Zhang, Wei; Santello, Marco

2010-07-07

Dexterous object manipulation requires anticipatory control of digit positions and forces. Despite extensive studies on sensorimotor learning of digit forces, how humans learn to coordinate digit positions and forces has never been addressed. Furthermore, the functional role of anticipatory modulation of digit placement to object properties remains to be investigated. We addressed these questions by asking human subjects (12 females, 12 males) to grasp and lift an inverted T-shaped object using precision grip at constrained or self-chosen locations. The task requirement was to minimize object roll during lift. When digit position was not constrained, subjects could have implemented many equally valid digit position-force coordination patterns. However, choice of digit placement might also have resulted in large trial-to-trial variability of digit position, hence challenging the extent to which the CNS could have relied on sensorimotor memories for anticipatory control of digit forces. We hypothesized that subjects would modulate digit placement for optimal force distribution and digit forces as a function of variable digit positions. All subjects learned to minimize object roll within the first three trials, and the unconstrained device was associated with significantly smaller grip forces but larger variability of digit positions. Importantly, however, digit load force modulation compensated for position variability, thus ensuring consistent object roll minimization on each trial. This indicates that subjects learned object manipulation by integrating sensorimotor memories with sensory feedback about digit positions. These results are discussed in the context of motor equivalence and sensorimotor integration of grasp kinematics and kinetics.
[Manufacture method and clinical application of minimally invasive dental implant guide template based on registration technology].

PubMed

Lin, Zeming; He, Bingwei; Chen, Jiang; D u, Zhibin; Zheng, Jingyi; Li, Yanqin

2012-08-01

To guide doctors in precisely positioning surgical operation, a new production method of minimally invasive implant guide template was presented. The mandible of patient was scanned by CT scanner, and three-dimensional jaw bone model was constructed based on CT images data The professional dental implant software Simplant was used to simulate the plant based on the three-dimensional CT model to determine the location and depth of implants. In the same time, the dental plaster models were scanned by stereo vision system to build the oral mucosa model. Next, curvature registration technology was used to fuse the oral mucosa model and the CT model, then the designed position of implant in the oral mucosa could be determined. The minimally invasive implant guide template was designed in 3-Matic software according to the design position of implant and the oral mucosa model. Finally, the template was produced by rapid prototyping. The three-dimensional registration technology was useful to fuse the CT data and the dental plaster data, and the template was accurate that could provide the doctors a guidance in the actual planting without cut-off mucosa. The guide template which fabricated by comprehensive utilization of three-dimensional registration, Simplant simulation and rapid prototyping positioning are accurate and can achieve the minimally invasive and accuracy implant surgery, this technique is worthy of clinical use.
Toward a preoperative planning tool for brain tumor resection therapies.

PubMed

Coffey, Aaron M; Miga, Michael I; Chen, Ishita; Thompson, Reid C

2013-01-01

Neurosurgical procedures involving tumor resection require surgical planning such that the surgical path to the tumor is determined to minimize the impact on healthy tissue and brain function. This work demonstrates a predictive tool to aid neurosurgeons in planning tumor resection therapies by finding an optimal model-selected patient orientation that minimizes lateral brain shift in the field of view. Such orientations may facilitate tumor access and removal, possibly reduce the need for retraction, and could minimize the impact of brain shift on image-guided procedures. In this study, preoperative magnetic resonance images were utilized in conjunction with pre- and post-resection laser range scans of the craniotomy and cortical surface to produce patient-specific finite element models of intraoperative shift for 6 cases. These cases were used to calibrate a model (i.e., provide general rules for the application of patient positioning parameters) as well as determine the current model-based framework predictive capabilities. Finally, an objective function is proposed that minimizes shift subject to patient position parameters. Patient positioning parameters were then optimized and compared to our neurosurgeon as a preliminary study. The proposed model-driven brain shift minimization objective function suggests an overall reduction of brain shift by 23 % over experiential methods. This work recasts surgical simulation from a trial-and-error process to one where options are presented to the surgeon arising from an optimization of surgical goals. To our knowledge, this is the first realization of an evaluative tool for surgical planning that attempts to optimize surgical approach by means of shift minimization in this manner.
A statistical model of false negative and false positive detection of phase singularities.

PubMed

Jacquemet, Vincent

2017-10-01

The complexity of cardiac fibrillation dynamics can be assessed by analyzing the distribution of phase singularities (PSs) observed using mapping systems. Interelectrode distance, however, limits the accuracy of PS detection. To investigate in a theoretical framework the PS false negative and false positive rates in relation to the characteristics of the mapping system and fibrillation dynamics, we propose a statistical model of phase maps with controllable number and locations of PSs. In this model, phase maps are generated from randomly distributed PSs with physiologically-plausible directions of rotation. Noise and distortion of the phase are added. PSs are detected using topological charge contour integrals on regular grids of varying resolutions. Over 100 × 10 6 realizations of the random field process are used to estimate average false negative and false positive rates using a Monte-Carlo approach. The false detection rates are shown to depend on the average distance between neighboring PSs expressed in units of interelectrode distance, following approximately a power law with exponents in the range of 1.14 to 2 for false negatives and around 2.8 for false positives. In the presence of noise or distortion of phase, false detection rates at high resolution tend to a non-zero noise-dependent lower bound. This model provides an easy-to-implement tool for benchmarking PS detection algorithms over a broad range of configurations with multiple PSs.
Emotional Disturbance

MedlinePlus

... body of research exists regarding methods of providing students with positive behavioral support (PBS) in the school environment, so that problem behaviors are minimized and positive, appropriate behaviors are ...
Integrated polymerase chain reaction/electrophoresis instrument

DOEpatents

Andresen, Brian D.

2000-01-01

A new approach and instrument for field identification of micro-organisms and DNA fragments using a small and disposable device containing integrated polymerase chain reaction (PCR) enzymatic reaction wells, attached capillary electrophoresis (CE) channels, detectors, and read-out all on/in a small hand-held package. The analysis instrument may be made inexpensively, for example, of plastic, and thus is disposable, which minimizes cross contamination and the potential for false positive identification between samples. In addition, it is designed for multiple users with individual applications. The integrated PCR/CE is manufactured by the PCR well and CE channels are "stamped" into plastic depressions where conductive coatings are made in the wells and ends of the CE microchannels to carry voltage and current to heat the PCR reaction mixtures and simultaneously draw DNA bands up the CE channels. Light is transmitted through the instrument at appropriate points and detects PCR bands and identifies DNA fragments by size (retention time) and quantifies each by the amount of light generated as each phototransistor positioned below each CE channel detects a passing band. The instrument is so compact that at least 100 PCR/CE reactions/analyses can be performed easily on one detection device.
Multislice CT Angiography in Renal Artery Stent Evaluation: Prospective Comparison with Intra-Arterial Digital Subtraction Angiography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Raza, Syed A.; Chughtai, Aamer R.; Wahba, Mona

2004-01-15

Purpose: To assess the role of multislice computed tomography angiography (MCTA) in the evaluation of renal artery stents, using intra-arterial digital subtraction angiography (DSA) as the gold standard. Methods: Twenty consecutive patients (15 men, 5 women) with 23 renal artery stents prospectively underwent both MCTA and DSA. Axial images, multiplanar reconstructions and maximum intensity projection images were used for diagnosis. The MCTA and DSA images were each interpreted without reference to the result of the other investigation. Results:The three cases of restenosis on DSA were detected correctly by MCTA; in 19 cases where MCTA showed a fully patent stent, themore » DSA was also negative. Sensitivity and negative predictive value (NPV) of MCTA were therefore 100%. In four cases, MCTA showed apparently minimal disease which was not shown on DSA. These cases are taken as false positive giving a specificity of 80% and a positive predictive value of 43%. Conclusion: The high sensitivity and NPV suggest MCTA may be useful as a noninvasive screen for renal artery stentrestenosis. MCTA detected mild disease in a few patients which was not confirmed on angiography.« less
The use of a tactile interface to convey position and motion perceptions

NASA Technical Reports Server (NTRS)

Rupert, A. H.; Guedry, F. E.; Reschke, M. F.

1994-01-01

Under normal terrestrial conditions, perception of position and motion is determined by central nervous system integration of concordant and redundant information from multiple sensory channels (somatosensory, vestibular, visual), which collectively yield vertical perceptions. In the acceleration environment experienced by the pilots, the somatosensory and vestibular sensors frequently present false information concerning the direction of gravity. When presented with conflicting sensory information, it is normal for pilots to experience episodes of disorientation. We have developed a tactile interface that obtains vertical roll and pitch information from a gyro-stabilized attitude indicator and maps this information in a one-to-one correspondence onto the torso of the body using a matrix of vibrotactors. This enables the pilot to continuously maintain an awareness of aircraft attitude without reference to visual cues, utilizing a sensory channel that normally operates at the subconscious level. Although initially developed to improve pilot spatial awareness, this device has obvious applications to 1) simulation and training, 2) nonvisual tracking of targets, which can reduce the need for pilots to make head movements in the high-G environment of aerial combat, and 3) orientation in environments with minimal somatosensory cues (e.g., underwater) or gravitational cues (e.g., space).
Development of species-specific hybridization probes for marine luminous bacteria by using in vitro DNA amplification.

PubMed Central

Wimpee, C F; Nadeau, T L; Nealson, K H

1991-01-01

By using two highly conserved region of the luxA gene as primers, polymerase chain reaction amplification methods were used to prepare species-specific probes against the luciferase gene from four major groups of marine luminous bacteria. Laboratory studies with test strains indicated that three of the four probes cross-reacted with themselves and with one or more of the other species at low stringencies but were specific for members of their own species at high stringencies. The fourth probe, generated from Vibrio harveyi DNA, cross-reacted with DNAs from two closely related species, V. orientalis and V. vulnificus. When nonluminous cultures were tested with the species-specific probes, no false-positive results were observed, even at low stringencies. Two field isolates were correctly identified as Photobacterium phosphoreum by using the species-specific hybridization probes at high stringency. A mixed probe (four different hybridization probes) used at low stringency gave positive results with all of the luminous bacteria tested, including the terrestrial species, Xenorhabdus luminescens, and the taxonomically distinct marine bacterial species Shewanella hanedai; minimal cross-hybridization with these species was seen at higher stringencies. Images PMID:1854194

Familial associations with paratuberculosis ELISA results in Texas Longhorn cattle.

PubMed

Osterstock, Jason B; Fosgate, Geoffrey T; Cohen, Noah D; Derr, James N; Manning, Elizabeth J B; Collins, Michael T; Roussel, Allen J

2008-05-25

The objective of this cross-sectional study was to estimate familial associations with paratuberculosis ELISA status in beef cattle. Texas Longhorn cattle (n=715) greater than 2years of age were sampled for paratuberculosis testing using ELISA and fecal culture. Diagnostic test results were indicative of substantial numbers of false-positive serological reactions consistent with environmental exposure to non-MAP Mycobacterium spp. Associations between ancestors and paratuberculosis ELISA status of offspring were assessed using conditional logistic regression. The association between ELISA status of the dam and her offspring was assessed using linear mixed-effect models. Significant associations were identified between some ancestors and offspring ELISA status. The odds of being classified as "suspect" or greater based on ELISA results were 4.6 times greater for offspring of dams with similarly increased S:P ratios. A significant positive linear association was also observed between dam and offspring log-transformed S:P ratios. Results indicate that there is familial aggregation of paratuberculosis ELISA results in beef cattle and suggest that genetic selection based on paratuberculosis ELISA status may decrease seroprevalence. However, genetic selection may have minimal effect on paratuberculosis control in herds with exposure to non-MAP Mycobacterium spp.
False-positive IgM for CMV in pregnant women with autoimmune disease: a novel prognostic factor for poor pregnancy outcome.

PubMed

De Carolis, S; Santucci, S; Botta, A; Garofalo, S; Martino, C; Perrelli, A; Salvi, S; Degennaro, Va; de Belvis, Ag; Ferrazzani, S; Scambia, G

2010-06-01

Our aims were to assess the frequency of false-positive IgM antibodies for cytomegalovirus in pregnant women with autoimmune diseases and in healthy women (controls) and to determine their relationship with pregnancy outcome. Data from 133 pregnancies in 118 patients with autoimmune diseases and from 222 pregnancies in 198 controls were assessed. When positive IgM for cytomegalovirus was detected, IgG avidity, cytomegalovirus isolation and polymerase chain reaction for CMV-DNA in maternal urine and amniotic fluid samples were performed in order to identify primary infection or false positivity. A statistically significantly higher rate of false-positive IgM was found in pregnancies with autoimmune diseases (16.5%) in comparison with controls (0.9%). A worse pregnancy outcome was observed among patients with autoimmune disease and false cytomegalovirus IgM in comparison with those without false positivity: earlier week of delivery (p = 0.017), lower neonatal birth weight (p = 0.0004) and neonatal birth weight percentile (p = 0.002), higher rate of intrauterine growth restriction (p = 0.02) and babies weighing less than 2000 g (p = 0.025) were encountered. The presence of false cytomegalovirus IgM in patients with autoimmune diseases could be used as a novel prognostic index of poor pregnancy outcome: it may reflect a non-specific activation of the immune system that could negatively affect pregnancy outcome. Lupus (2010) 19, 844-849.
[Analysis of false-positive reaction for bacterial detection of blood samples with the automated microbial detection system BacT/ALERT 3D].

PubMed

Zhu, Li-Wei; Yang, Xue-Mei; Xu, Xiao-Qin; Xu, Jian; Lu, Huang-Jun; Yan, Li-Xing

2008-10-01

This study was aimed to analyze the results of false positive reaction in bacterial detection of blood samples with BacT/ALERT 3D system, to evaluate the specificity of this system, and to decrease the false positive reaction. Each reaction flasks in past five years were processed for bacteria isolation and identification. When the initial cultures were positive, the remaining samples and the corresponding units were recultured if still available. 11395 blood samples were detected. It is worthy of note that the incubator temperature should be stabilized, avoiding fluctuation; when the cultures were alarmed, the reaction flasks showed be kept some hours for further incubation so as to trace a sharply increasing signal to support the judgement of true bacterial growth. The results indicated that 122 samples (1.07%) wee positive at initial culture, out of them 107 samples (88.7%) were found bacterial, and 15 samples (12.3%) were found nothing. The detection curves of positive samples resulted from bacterial growth showed ascent. In conclusion, maintenance of temperature stability and avoidance of temperature fluctuation in incubator could decrease the occurrence of false-positive reaction in detection process. The reaction flasks with positive results at initial culture should be recultured, and whether existence of a sharply ascending logarilhimic growth phase in bacterial growth curve should be further detected, which are helpful to distinguish false-positive reactions from true positive, and thus increase the specificity of the BacT/ALERT system.
False-Positive Tuberculin Skin Test Results Among Low-Risk Healthcare Workers Following Implementation of Fifty-Dose Vials of Purified Protein Derivative.

PubMed

Collins, Jeffrey M; Hunter, Mary; Gordon, Wanda; Kempker, Russell R; Blumberg, Henry M; Ray, Susan M

2018-06-01

Following large declines in tuberculosis transmission the United States, large-scale screening programs targeting low-risk healthcare workers are increasingly a source of false-positive results. We report a large cluster of presumed false-positive tuberculin skin test results in healthcare workers following a change to 50-dose vials of Tubersol tuberculin.Infect Control Hosp Epidemiol 2018;39:750-752.
Algorithm of reducing the false positives in IDS based on correlation Analysis

NASA Astrophysics Data System (ADS)

Liu, Jianyi; Li, Sida; Zhang, Ru

2018-03-01

This paper proposes an algorithm of reducing the false positives in IDS based on correlation Analysis. Firstly, the algorithm analyzes the distinguishing characteristics of false positives and real alarms, and preliminary screen the false positives; then use the method of attribute similarity clustering to the alarms and further reduces the amount of alarms; finally, according to the characteristics of multi-step attack, associated it by the causal relationship. The paper also proposed a reverse causation algorithm based on the attack association method proposed by the predecessors, turning alarm information into a complete attack path. Experiments show that the algorithm simplifies the number of alarms, improve the efficiency of alarm processing, and contribute to attack purposes identification and alarm accuracy improvement.
Objective definition of rainfall intensity-duration thresholds for post-fire flash floods and debris flows in the area burned by the Waldo Canyon fire, Colorado, USA

USGS Publications Warehouse

Staley, Dennis M.; Gartner, Joseph E.; Kean, Jason W.

2015-01-01

We present an objectively defined rainfall intensity-duration (I-D) threshold for the initiation of flash floods and debris flows for basins recently burned in the 2012 Waldo Canyon fire near Colorado Springs, Colorado, USA. Our results are based on 453 rainfall records which include 8 instances of hazardous flooding and debris flow from 10 July 2012 to 14 August 2013. We objectively defined the thresholds by maximizing the number of correct predictions of debris flow or flood occurrence while minimizing the rate of both Type I (false positive) and Type II (false negative) errors. The equation I = 11.6D−0.7 represents the I-D threshold (I, in mm/h) for durations (D, in hours) ranging from 0.083 h (5 min) to 1 h for basins burned by the 2012 Waldo Canyon fire. As periods of high-intensity rainfall over short durations (less than 1 h) produced all of the debris flow and flood events, real-time monitoring of rainfall conditions will result in very short lead times for early-warning. Our results highlight the need for improved forecasting of the rainfall rates during short-duration, high-intensity convective rainfall events.
Penicillin allergy: optimizing diagnostic protocols, public health implications, and future research needs.

PubMed

Macy, Eric

2015-08-01

Unverified penicillin allergy is being increasingly recognized as a public health concern. The ideal protocol for verifying true clinically significant IgE-mediated penicillin allergy needs to use only commercially available materials, be well tolerated and easy to perform in both the inpatient and outpatient settings, and minimize false-positive determinations. This review concentrates on articles published in 2013 and 2014 that present new data relating to the diagnosis and management of penicillin allergy. Penicillin allergy can be safely evaluated at this time, in patients with an appropriate clinical history of penicillin allergy, using only penicilloyl-poly-lysine and native penicillin G as skin test reagents, if an oral challenge with amoxicillin 250 mg, followed by 1 h of observation, is given to all skin test negative individuals. Millions of individuals falsely labeled with penicillin allergy need to be evaluated to safely allow them to use penicillin-class antibiotics and avoid morbidity associated with penicillin avoidance. Further research is needed to determine optimal protocol(s). There will still be a 1-2% rate of adverse reactions reported with all future therapeutic penicillin-class antibiotic use, even with optimal methods used to determine acute penicillin tolerance. Only a small minority of these new reactions will be IgE-mediated.
How accurate is our clinical prediction of "minimal prostate cancer"?

PubMed

Leibovici, Dan; Shikanov, Sergey; Gofrit, Ofer N; Zagaja, Gregory P; Shilo, Yaniv; Shalhav, Arieh L

2013-07-01

Recommendations for active surveillance versus immediate treatment for low risk prostate cancer are based on biopsy and clinical data, assuming that a low volume of well-differentiated carcinoma will be associated with a low progression risk. However, the accuracy of clinical prediction of minimal prostate cancer (MPC) is unclear. To define preoperative predictors for MPC in prostatectomy specimens and to examine the accuracy of such prediction. Data collected on 1526 consecutive radical prostatectomy patients operated in a single center between 2003 and 2008 included: age, body mass index, preoperative prostate-specific antigen level, biopsy Gleason score, clinical stage, percentage of positive biopsy cores, and maximal core length (MCL) involvement. MPC was defined as < 5% of prostate volume involvement with organ-confined Gleason score < or = 6. Univariate and multivariate logistic regression analyses were used to define independent predictors of minimal disease. Classification and Regression Tree (CART) analysis was used to define cutoff values for the predictors and measure the accuracy of prediction. MPC was found in 241 patients (15.8%). Clinical stage, biopsy Gleason's score, percent of positive biopsy cores, and maximal involved core length were associated with minimal disease (OR 0.42, 0.1, 0.92, and 0.9, respectively). Independent predictors of MPC included: biopsy Gleason score, percent of positive cores and MCL (OR 0.21, 095 and 0.95, respectively). CART showed that when the MCL exceeded 11.5%, the likelihood of MPC was 3.8%. Conversely, when applying the most favorable preoperative conditions (Gleason < or = 6, < 20% positive cores, MCL < or = 11.5%) the chance of minimal disease was 41%. Biopsy Gleason score, the percent of positive cores and MCL are independently associated with MPC. While preoperative prediction of significant prostate cancer was accurate, clinical prediction of MPC was incorrect 59% of the time. Caution is necessary when implementing clinical data as selection criteria for active surveillance.
Quantum scattering in one-dimensional systems satisfying the minimal length uncertainty relation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bernardo, Reginald Christian S., E-mail: rcbernardo@nip.upd.edu.ph; Esguerra, Jose Perico H., E-mail: jesguerra@nip.upd.edu.ph

In quantum gravity theories, when the scattering energy is comparable to the Planck energy the Heisenberg uncertainty principle breaks down and is replaced by the minimal length uncertainty relation. In this paper, the consequences of the minimal length uncertainty relation on one-dimensional quantum scattering are studied using an approach involving a recently proposed second-order differential equation. An exact analytical expression for the tunneling probability through a locally-periodic rectangular potential barrier system is obtained. Results show that the existence of a non-zero minimal length uncertainty tends to shift the resonant tunneling energies to the positive direction. Scattering through a locally-periodic potentialmore » composed of double-rectangular potential barriers shows that the first band of resonant tunneling energies widens for minimal length cases when the double-rectangular potential barrier is symmetric but narrows down when the double-rectangular potential barrier is asymmetric. A numerical solution which exploits the use of Wronskians is used to calculate the transmission probabilities through the Pöschl–Teller well, Gaussian barrier, and double-Gaussian barrier. Results show that the probability of passage through the Pöschl–Teller well and Gaussian barrier is smaller in the minimal length cases compared to the non-minimal length case. For the double-Gaussian barrier, the probability of passage for energies that are more positive than the resonant tunneling energy is larger in the minimal length cases compared to the non-minimal length case. The approach is exact and applicable to many types of scattering potential.« less
[Molecular beacon based PNA-FISH method combined with fluorescence scanning for rapid detection of Listeria monocytogenes].

PubMed

Wu, Shan; Zhang, Xiaofeng; Shuai, Jiangbing; Li, Ke; Yu, Huizhen; Jin, Chenchen

2016-07-04

To simplify the PNA-FISH (Peptide nucleic acid-fluorescence in situ hybridization) test, molecular beacon based PNA probe combined with fluorescence scanning detection technology was applied to replace the original microscope observation to detect Listeria monocytogenes The 5′ end and 3′ end of the L. monocytogenes specific PNA probes were labeled with the fluorescent group and the quenching group respectively, to form a molecular beacon based PNA probe. When PNA probe used for fluorescence scanning and N1 treatment as the control, the false positive rate was 11.4%, and the false negative rate was 0; when N2 treatment as the control, the false positive rate decreased to 4.3%, but the false negative rate rose to 18.6%. When beacon based PNA probe used for fluorescence scanning, taken N1 treatment as blank control, the false positive rate was 8.6%, and the false negative rate was 1.4%; taken N2 treatment as blank control, the false positive rate was 5.7%, and the false negative rate was 1.4%. Compared with PNA probe, molecular beacon based PNA probe can effectively reduce false positives and false negatives. The success rates of hybridization of the two PNA probes were 83.3% and 95.2% respectively; and the rates of the two beacon based PNA probes were 91.7% and 90.5% respectively, which indicated that labeling the both ends of the PNA probe dose not decrease the hybridization rate with the target bacteria. The combination of liquid phase PNA-FISH and fluorescence scanning method, can significantly improve the detection efficiency.
Interval from prostate biopsy to radical prostatectomy does not affect immediate operative outcomes for open or minimally invasive approach.

PubMed

Park, Bumsoo; Choo, Seol Ho; Jeon, Hwang Gyun; Jeong, Byong Chang; Seo, Seong Il; Jeon, Seong Soo; Lee, Hyun Moo; Choi, Han Yong

2014-12-01

Traditionally, urologists recommend an interval of at least 4 weeks after prostate biopsy before radical prostatectomy. The aim of our study was to evaluate whether the interval from prostate biopsy to radical prostatectomy affects immediate operative outcomes, with a focus on differences in surgical approach. The study population of 1,848 radical prostatectomy patients was divided into two groups according to the surgical approach: open or minimally invasive. Open group included perineal and retropubic approach, and minimally invasive group included laparoscopic and robotic approach. The cut-off of the biopsy-to-surgery interval was 4 weeks. Positive surgical margin status, operative time and estimated blood loss were evaluated as endpoint parameters. In the open group, there were significant differences in operative time and estimated blood loss between the <4-week and ≥4-week interval subgroups, but there was no difference in positive margin rate. In the minimally invasive group, there were no differences in the three outcome parameters between the two subgroups. Multivariate analysis revealed that the biopsy-to-surgery interval was not a significant factor affecting immediate operative outcomes in both open and minimally invasive groups, with the exception of the interval ≥4 weeks as a significant factor decreasing operative time in the minimally invasive group. In conclusion, performing open or minimally invasive radical prostatectomy within 4 weeks of prostate biopsy is feasible for both approaches, and is even beneficial for minimally invasive radical prostatectomy to reduce operative time.
Implications of false-positive results for future cancer screenings.

PubMed

Taksler, Glen B; Keating, Nancy L; Rothberg, Michael B

2018-06-01

False-positive cancer screening results may affect a patient's willingness to obtain future screening. The authors conducted logistic regression analysis of 450,484 person-years of electronic medical records (2006-2015) in 92,405 individuals aged 50 to 75 years. Exposures were false-positive breast, prostate, or colorectal cancer screening test results (repeat breast imaging or negative breast biopsy ≤3 months after screening mammography, repeat prostate-specific antigen [PSA] test ≤3 months after PSA test result ≥4.0 ng/mL or negative prostate biopsy ≤3 months after any PSA result, or negative colonoscopy [without biopsy/polypectomy] ≤6 months after a positive fecal occult blood test). Outcomes were up-to-date status with breast or colorectal cancer screening. Covariates included prior screening history, clinical information (eg, family history, obesity, and smoking status), comorbidity, and demographics. Women were more likely to be up to date with breast cancer screening if they previously had false-positive mammography findings (adjusted odds ratio [AOR], 1.43 [95% confidence interval, 1.34-1.51] without breast biopsy and AOR, 2.02 [95% confidence interval, 1.56-2.62] with breast biopsy; both P<.001). The same women were more likely to be up to date with colorectal cancer screening (AOR range, 1.25-1.47 depending on breast biopsy; both P<.001). Men who previously had false-positive PSA testing were more likely to be up to date with colorectal cancer screening (AOR, 1.22 [P = .039] without prostate imaging/biopsy and AOR, 1.60 [P = .028] with imaging/biopsy). Results were stronger for individuals with more false-positive results (all P≤.005). However, women with previous false-positive colorectal cancer fecal occult blood test screening results were found to be less likely to be up to date with breast cancer screening (AOR, 0.73; P<.001). Patients who previously had a false-positive breast or prostate cancer screening test were more likely to engage in future screening. Cancer 2018;124:2390-8. © 2018 American Cancer Society. © 2018 American Cancer Society.
False-Positive Xpert MTB/RIF Results in Retested Patients with Previous Tuberculosis: Frequency, Profile, and Prospective Clinical Outcomes.

PubMed

Theron, Grant; Venter, Rouxjeane; Smith, Liezel; Esmail, Aliasgar; Randall, Philippa; Sood, Vishesh; Oelfese, Suzette; Calligaro, Greg; Warren, Robin; Dheda, Keertan

2018-03-01

Globally, Xpert MTB/RIF (Xpert) is the most widely used PCR test for the diagnosis of tuberculosis (TB). Positive results in previously treated patients, which are due to old DNA or active disease, are a diagnostic dilemma. We prospectively retested sputum from 238 patients, irrespective of current symptoms, who were previously diagnosed to be Xpert positive and treated successfully. Patients who retested as Xpert positive and culture negative were exhaustively investigated (repeat culture, chest radiography, bronchoscopy with bronchoalveolar lavage, long-term clinical follow-up). We evaluated whether the duration since previous treatment completion, mycobacterial burden (the Xpert cycle threshold [ C T ] value), and reclassification of Xpert-positive results with a very low semiquantitation level to Xpert-negative results reduced the rate of false positivity. A total of 229/238 (96%) of patients were culture negative. Sixteen of 229 (7%) were Xpert positive a median of 11 months (interquartile range, 5 to 19 months) after treatment completion. The specificity was 93% (95% confidence interval [CI], 89 to 96%). Nine of 15 (40%) Xpert-positive, culture-negative patients reverted to Xpert negative after 2 to 3 months (1 patient declined further participation). Patients with false-positive Xpert results had a lower mycobacterial burden than patients with true-positive Xpert results ( C T , 28.7 [95% CI, 27.2 to 30.4] versus 17.6 [95% CI, 16.9 to 18.2]; P < 0.001), an increased likelihood of a chest radiograph not compatible with active TB (5/15 patients versus 0/5 patients; P = 0.026), and less-viscous sputum (15/16 patients versus 2/5 patients whose sputum was graded as mucoid or less; P = 0.038). All patients who initially retested as Xpert positive and culture negative ("Xpert false positive") were clinically well without treatment after follow-up. The duration since the previous treatment poorly predicted false-positive results (a duration of ≤2 years identified only 66% of patients with false-positive results). Reclassifying Xpert-positive results with a very low semiquantitation level to Xpert negative improved the specificity (+3% [95% CI, +2 to +5%]) but reduced the sensitivity (-10% [95% CI, -4 to -15%]). Patients with previous TB retested with Xpert can have false-positive results and thus not require treatment. These data inform clinical practice by highlighting the challenges in interpreting Xpert-positive results, underscore the need for culture, and have implications for next-generation ultrasensitive tests. Copyright © 2018 American Society for Microbiology.
Case Reports of Aripiprazole Causing False-Positive Urine Amphetamine Drug Screens in Children.

PubMed

Kaplan, Justin; Shah, Pooja; Faley, Brian; Siegel, Mark E

2015-12-01

Urine drug screens (UDSs) are used to identify the presence of certain medications. One limitation of UDSs is the potential for false-positive results caused by cross-reactivity with other substances. Amphetamines have an extensive list of cross-reacting medications. The literature contains reports of false-positive amphetamine UDSs with multiple antidepressants and antipsychotics. We present 2 cases of presumed false-positive UDSs for amphetamines after ingestion of aripiprazole. Case 1 was a 16-month-old girl who accidently ingested 15 to 45 mg of aripiprazole. She was lethargic and ataxic at home with 1 episode of vomiting containing no identifiable tablets. She remained sluggish with periods of irritability and was admitted for observation. UDS on 2 consecutive days came back positive for amphetamines. Case 2 was of a 20-month-old girl who was brought into the hospital after accidental ingestion of an unknown quantity of her father's medications which included aripiprazole. UDS on the first day of admission came back positive only for amphetamines. Confirmatory testing with gas chromatography-mass spectrometry (GC-MS) on the blood and urine samples were also performed for both patients on presentation to detect amphetamines and were subsequently negative. Both patients returned to baseline and were discharged from the hospital. To our knowledge, these cases represent the first reports of false-positive amphetamine urine drug tests with aripiprazole. In both cases, aripiprazole was the drug with the highest likelihood of causing the positive amphetamine screen. The implications of these false-positives include the possibility of unnecessary treatment and monitoring of patients. Copyright © 2015 by the American Academy of Pediatrics.
Multiple positive normalized solutions for nonlinear Schrödinger systems

NASA Astrophysics Data System (ADS)

Gou, Tianxiang; Jeanjean, Louis

2018-05-01

We consider the existence of multiple positive solutions to the nonlinear Schrödinger systems set on , under the constraint Here are prescribed, , and the frequencies are unknown and will appear as Lagrange multipliers. Two cases are studied, the first when , the second when In both cases, assuming that is sufficiently small, we prove the existence of two positive solutions. The first one is a local minimizer for which we establish the compactness of the minimizing sequences and also discuss the orbital stability of the associated standing waves. The second solution is obtained through a constrained mountain pass and a constrained linking respectively.
Convergence of Weak Kähler-Ricci Flows on Minimal Models of Positive Kodaira Dimension

NASA Astrophysics Data System (ADS)

Eyssidieux, Phylippe; Guedj, Vincent; Zeriahi, Ahmed

2018-02-01

Studying the behavior of the Kähler-Ricci flow on mildly singular varieties, one is naturally lead to study weak solutions of degenerate parabolic complex Monge-Ampère equations. In this article, the third of a series on this subject, we study the long term behavior of the normalized Kähler-Ricci flow on mildly singular varieties of positive Kodaira dimension, generalizing results of Song and Tian who dealt with smooth minimal models.
Validation of automatic wheeze detection in patients with obstructed airways and in healthy subjects.

PubMed

Guntupalli, Kalpalatha K; Alapat, Philip M; Bandi, Venkata D; Kushnir, Igal

2008-12-01

Computerized lung-sound analysis is a sensitive and quantitative method to identify wheezing by its typical pattern on spectral analysis. We evaluated the accuracy of the VRI, a multi-sensor, computer-based device with an automated technique of wheeze detection. The method was validated in 100 sound files from seven subjects with asthma or chronic obstructive pulmonary disease and seven healthy subjects by comparison of auscultation findings, examination of audio files, and computer detection of wheezes. Three blinded physicians identified 40 sound files with wheezes and 60 sound files without wheezes. Sensitivity and specificity were 83% and 85%, respectively. Negative predictive value and positive predictive value were 89% and 79%, respectively. Overall inter-rater agreement was 84%. False positive cases were found to contain sounds that simulate wheezes, such as background noises with high frequencies or strong noises from the throat that could be heard and identified without a stethoscope. The present findings demonstrate that the wheeze detection algorithm has good accuracy, sensitivity, specificity, negative predictive value and positive predictive value for wheeze detection in regional analyses with a single sensor and multiple sensors. Results are similar to those reported in the literature. The device is user-friendly, requires minimal patient effort, and, distinct from other devices, it provides a dynamic image of breath sound distribution with wheeze detection output in less than 1 minute.
Detection of Herpesvirus anguillae (AngHV-1) in European eel Anguilla anguilla (L.) originating from northern Poland-assessment of suitability of selected diagnostic methods.

PubMed

Nguyen, Tuan Thuc; Jin, Yeonhwa; Kiełpińska, Jolanta; Bergmann, Sven M; Lenk, Matthias; Panicz, Remigiusz

2017-11-01

The Community Action Plan requests EU member states to implement measures that ensure the recovery of the severely depleted European eel stocks. One of the main threats is posed by Anguillid herpesvirus 1 (AngHV-1) leading to increased mortality in both wild and farmed eels. Following recommendations of the OIE to minimize the risk of obtaining false-negative results, the main aim of the study was to optimize diagnostic methods for AngHV-1 detection using conventional PCR, nested PCR and in situ hybridization assay. While 53.3% of the individual organ samples were tested positive for AngHV-1 by PCR, the additional virus analysis via nested PCR revealed that the actual prevalence was 93.3%. In the cell cultivation passages, a cytopathic effect was hardly found in the first two rounds. In the third passage onto cell cultures, a lytic CPE was detected. The identification and confirmation of the viruses obtained from cell cultures as well as directly from the organ tissues were proceeded by PCR, nested PCR and sequencing of the PCR products. While no positive signal was detectable in the first round by PCR using samples from the third cell culture passages, the nested PCR provided weak but visible positive signals. © 2017 John Wiley & Sons Ltd.
Effect of protocol-related variables and women's characteristics on the cumulative false-positive risk in breast cancer screening

PubMed Central

Román, R.; Sala, M.; Salas, D.; Ascunce, N.; Zubizarreta, R.; Castells, X.

2012-01-01

Background: Reducing the false-positive risk in breast cancer screening is important. We examined how the screening-protocol and women's characteristics affect the cumulative false-positive risk. Methods: This is a retrospective cohort study of 1 565 364 women aged 45–69 years who underwent 4 739 498 screening mammograms from 1990 to 2006. Multilevel discrete hazard models were used to estimate the cumulative false-positive risk over 10 sequential mammograms under different risk scenarios. Results: The factors affecting the false-positive risk for any procedure and for invasive procedures were double mammogram reading [odds ratio (OR) = 2.06 and 4.44, respectively], two mammographic views (OR = 0.77 and 1.56, respectively), digital mammography (OR = 0.83 for invasive procedures), premenopausal status (OR = 1.31 and 1.22, respectively), use of hormone replacement therapy (OR = 1.03 and 0.84, respectively), previous invasive procedures (OR = 1.52 and 2.00, respectively), and a familial history of breast cancer (OR = 1.18 and 1.21, respectively). The cumulative false-positive risk for women who started screening at age 50–51 was 20.39% [95% confidence interval (CI) 20.02–20.76], ranging from 51.43% to 7.47% in the highest and lowest risk profiles, respectively. The cumulative risk for invasive procedures was 1.76% (95% CI 1.66–1.87), ranging from 12.02% to 1.58%. Conclusions: The cumulative false-positive risk varied widely depending on the factors studied. These findings are relevant to provide women with accurate information and to improve the effectiveness of screening programs. PMID:21430183
Factors associated with a second deferral among donors eligible for re-entry after a false-positive screening test for syphilis, HCV, HBV and HIV.

PubMed

Grégoire, Y; Germain, M; Delage, G

2018-05-01

Since 25 May 2010, all donors at our blood centre who tested false-positive for HIV, HBV, HCV or syphilis are eligible for re-entry after further testing. Donors who have a second false-positive screening test, either during qualification for or after re-entry, are deferred for life. This study reports on factors associated with the occurrence of such deferrals. Rates of second false-positive results were compared by year of deferral, transmissible disease marker, gender, age, donor status (new or repeat) and testing platform (same or different) both at qualification for re-entry and afterwards. Chi-square tests were used to compare proportions. Cox regression was used for multivariate analyses. Participation rates in the re-entry programme were 42·1%: 25·6% failed to qualify for re-entry [different platform: 2·7%; same platform: 42·9% (P < 0·0001)]. After re-entry, rates of deferral for second false-positive results were 8·4% after 3 years [different platform: 1·8%; same platform: 21·4% (P < 0·0001)]. Deferral rates were higher for HIV and HCV than for HBV at qualification when tested on the same platform. The risk, when analysed by multivariate analyses, of a second deferral for a false-positive result, both at qualification and 3 years after re-entry, was lower for donors deferred on a different platform; this risk was higher for HIV, HCV and syphilis than for HBV and for new donors if tested on the same platform. Re-entry is more often successful when donors are tested on a testing platform different from the one on which they obtained their first false-positive result. © 2018 International Society of Blood Transfusion.

The probability of false positives in zero-dimensional analyses of one-dimensional kinematic, force and EMG trajectories.

PubMed

Pataky, Todd C; Vanrenterghem, Jos; Robinson, Mark A

2016-06-14

A false positive is the mistake of inferring an effect when none exists, and although α controls the false positive (Type I error) rate in classical hypothesis testing, a given α value is accurate only if the underlying model of randomness appropriately reflects experimentally observed variance. Hypotheses pertaining to one-dimensional (1D) (e.g. time-varying) biomechanical trajectories are most often tested using a traditional zero-dimensional (0D) Gaussian model of randomness, but variance in these datasets is clearly 1D. The purpose of this study was to determine the likelihood that analyzing smooth 1D data with a 0D model of variance will produce false positives. We first used random field theory (RFT) to predict the probability of false positives in 0D analyses. We then validated RFT predictions via numerical simulations of smooth Gaussian 1D trajectories. Results showed that, across a range of public kinematic, force/moment and EMG datasets, the median false positive rate was 0.382 and not the assumed α=0.05, even for a simple two-sample t test involving N=10 trajectories per group. The median false positive rate for experiments involving three-component vector trajectories was p=0.764. This rate increased to p=0.945 for two three-component vector trajectories, and to p=0.999 for six three-component vectors. This implies that experiments involving vector trajectories have a high probability of yielding 0D statistical significance when there is, in fact, no 1D effect. Either (a) explicit a priori identification of 0D variables or (b) adoption of 1D methods can more tightly control α. Copyright © 2016 Elsevier Ltd. All rights reserved.
Development of Technologies for Early Detection and Stratification of Breast Cancer

DTIC Science & Technology

2012-10-01

at the time of screening, and has an 8-10% false positive rate.3 These drawbacks lead to inaccurate patient diagnosis, which can allow potentially...95% recovery efficiency. Furthermore, using whole blood from healthy donors, we determined we have a zero false positive rate; that is, we have not...detected a single false positive event out of the dozen samples we ran. The technology we developed here is not only useful for the isolation of CTCs
False Positives in Exoplanet Detection

NASA Astrophysics Data System (ADS)

Leuquire, Jacob; Kasper, David; Jang-Condell, Hannah; Kar, Aman; Sorber, Rebecca; Suhaimi, Afiq; KELT (Kilodegree Extremely Little Telescope)

2018-06-01

Our team at the University of Wyoming uses a 0.6 m telescope at RBO (Red Buttes Observatory) to help confirm results on potential exoplanet candidates from low resolution, wide field surveys shared by the KELT (Kilodegree Extremely Little Telescope) team. False positives are common in this work. We carry out transit photometry, and this method comes with special types of false positives. The most common false positive seen at the confirmation level is an EB (eclipsing binary). Low resolution images are great in detecting multiple sources for photometric dips in light curves, but they lack the precision to decipher single targets at an accurate level. For example, target star KC18C030621 needed RBO’s photometric precision to determine there was a nearby EB causing exoplanet type light curves. Identifying false positives with our telescope is important work because it helps eliminate the waste of time taken by more expensive telescopes trying to rule out negative candidate stars. It also furthers the identification of other types of photometric events, like eclipsing binaries, so they can be studied on their own.
Oxybuprocaine induces a false-positive response in immunochromatographic SAS Adeno Test.

PubMed

Hoshino, Takeshi; Takanashi, Taiji; Okada, Morio; Uchida, Sunao

2002-04-01

To investigate whether a solution of oxybuprocaine hydrochloride, 0.4%, results in a false-positive response in an immunochromatographic SAS Adeno Test. Experimental study. Physiologic saline and 2% lidocaine. Each chemical (100 microl) was diluted in a transport medium. Five drops (200 microl) of the resultant solution were dispensed into the round sample well of a test device. Fifteen samples were tested in each group. Ten minutes after the start of the test, a colored line in the "specimen" portion of the test membrane was visually read as positive or negative by a masked technician. No positive reaction was observed in the control groups (physiologic saline and lidocaine). A false-positive reaction was observed in six samples (33.3%) in the oxybuprocaine group. The positive rate was significantly higher in the oxybuprocaine group compared with those in control groups (P = 0.0062, Fisher's extract probability test). Oxybuprocaine may induce a false-positive reaction in an immunochromatographic SAS Adeno Test. We recommend the use of lidocaine, instead of oxybuprocaine, for local anesthesia in taking eye swabs from patients with suspected adenovirus infection.
A deep learning approach for the analysis of masses in mammograms with minimal user intervention.

PubMed

Dhungel, Neeraj; Carneiro, Gustavo; Bradley, Andrew P

2017-04-01

We present an integrated methodology for detecting, segmenting and classifying breast masses from mammograms with minimal user intervention. This is a long standing problem due to low signal-to-noise ratio in the visualisation of breast masses, combined with their large variability in terms of shape, size, appearance and location. We break the problem down into three stages: mass detection, mass segmentation, and mass classification. For the detection, we propose a cascade of deep learning methods to select hypotheses that are refined based on Bayesian optimisation. For the segmentation, we propose the use of deep structured output learning that is subsequently refined by a level set method. Finally, for the classification, we propose the use of a deep learning classifier, which is pre-trained with a regression to hand-crafted feature values and fine-tuned based on the annotations of the breast mass classification dataset. We test our proposed system on the publicly available INbreast dataset and compare the results with the current state-of-the-art methodologies. This evaluation shows that our system detects 90% of masses at 1 false positive per image, has a segmentation accuracy of around 0.85 (Dice index) on the correctly detected masses, and overall classifies masses as malignant or benign with sensitivity (Se) of 0.98 and specificity (Sp) of 0.7. Copyright © 2017 Elsevier B.V. All rights reserved.
Visual field progression in glaucoma: what is the specificity of the Guided Progression Analysis?

PubMed

Artes, Paul H; O'Leary, Neil; Nicolela, Marcelo T; Chauhan, Balwantray C; Crabb, David P

2014-10-01

To estimate the specificity of the Guided Progression Analysis (GPA) (Carl Zeiss Meditec, Dublin, CA) in individual patients with glaucoma. Observational cohort study. Thirty patients with open-angle glaucoma. In 30 patients with open-angle glaucoma, 1 eye (median mean deviation [MD], -2.5 decibels [dB]; interquartile range, -4.4 to -1.3 dB) was tested 12 times over 3 months (Humphrey Field Analyzer, Carl Zeiss Meditec; SITA Standard, 24-2). "Possible progression" and "likely progression" were determined with the GPA. These analyses were repeated after the order of the tests had been randomly rearranged (1000 unique permutations). Rate of false-positive alerts of "possible progression" and "likely progression" with the GPA. On average, the specificity of the GPA "likely progression" alert was high-for the entire sample, the mean rate of false-positive alerts after 10 follow-up tests was 2.6%. With "possible progression," the specificity was considerably lower (false-positive rate, 18.5%). Most important, the cumulative rate of false-positive alerts varied substantially among patients, from <1% to 80% with "possible progression" and from <0.1% to 20% with "likely progression." Factors associated with false-positive alerts were visual field variability (standard deviation of MD, Spearman's rho = 0.41, P<0.001) and the reliability indices (proportion of false-positive and false-negative responses, fixation losses, rho>0.31, P≤0.10). On average, progression criteria currently used in the GPA have high specificity, but some patients are more likely to show false-positive alerts than others. This is a natural consequence of population-based change criteria and may not matter in clinical trials and studies in which large groups of patients are compared. However, it must be considered when the GPA is used in clinical practice where specificity needs to be controlled for individual patients. Copyright © 2014 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.
Do positive schizotypal symptoms predict false perceptual experiences in nonclinical populations?

PubMed

Tsakanikos, Elias; Reed, Phil

2005-12-01

We examined whether positive schizotypy (i.e., reports of hallucinatory and delusional-like experiences) in nonclinical participants could predict false perceptual experiences during detection of fast-moving words beyond a possible response bias. The participants (N = 160) were assigned to one of two conditions: they were asked either to make presence/absence judgments (loose criterion) or to read aloud every detected word (strict criterion). Regression analysis showed that high levels of positive schizotypy predicted false alarms in the loose condition and false perceptions of words in the strict condition. The obtained effects were independent of detection accuracy, task order, impulsivity, and social desirability. We discuss the results in the context of information processing biases linked to the positive symptomatology of schizophrenia. Clinical and theoretical implications are also considered.
False Memory in Adults With ADHD: A Comparison Between Subtypes and Normal Controls.

PubMed

Soliman, Abdrabo Moghazy; Elfar, Rania Mohamed

2017-10-01

To examine the performance on the Deese-Roediger-McDermott task of adults divided into ADHD subtypes and compares their performance to that of healthy controls to examine whether adults with ADHD are more susceptible to the production of false memories under experimental conditions. A total of 128 adults with ADHD (50% females), classified into three Diagnostic and Statistical Manual of Mental Disorders (4th ed.; DSM-IV-TR) subtypes, were compared with 48 controls. The results indicated that the ADHD participants recalled and recognized fewer studied words than the controls, the ADHD groups produced more false memories than the control group, no differences in either the false positives or the false negatives. The ADHD-combined (ADHD-CT) group recognized significantly more critical words than the control, ADHD-predominantly inattentive (ADHD-IA), and ADHD-predominantly hyperactive-impulsive (ADHD-HI) groups. The ADHD groups recalled and recognized more false positives, were more confident in their false responses, and displayed more knowledge corruption than the controls. The ADHD-CT group recalled and recognized more false positives than the other ADHD groups. The adults with ADHD have more false memories than the controls and that false memory formation varied with the ADHD subtypes.
Investigating Clinically and Scientifically Useful Cut Points on the Compulsive Sexual Behavior Inventory

PubMed Central

Miner, Michael H.; Raymond, Nancy; Coleman, Eli; Romine, Rebecca Swinburne

2017-01-01

Introduction One of the major obstacles to conducting epidemiological research and determining the incidence and prevalence of compulsive sexual behavior has been the lack of relevant, empirically derived cut points on the various instruments that have been used to measure the concept. Aim To further develop the Compulsive Sexual Behavior Inventory (CSBI) through exploring predictive validity and developing an empirically determined and clinically useful cut point for defining CSB. Methods A sample of 242 men who have sex with men was recruited from various sites in a moderate-size Midwestern city. Participants were assigned to a CSB group or a control group using an interview for the diagnosis that was patterned after the Structured Clinical Interview for the Diagnostic and Statistical Manual for Mental Disorders, Fourth Edition. The 22-item CSBI was administered as part of a larger battery of self-report inventories. Main Outcome Measures ROC analyses were used to compute AUC measures to ascertain predictive validity of the total scale, the control subscale and the violence subscale. Cut-points were determined through consensus of experts balancing sensitivity and specificity as determined by ROC curves. Results Analyses indicated that the 22-item CSBI was a good predictor of group membership, as was the 13-item control subscale. The Violence subscale added little to the predictive accuracy of the instrument and thus, it likely measures something other than CSB. Two relevant cut points were found, one that minimized false negatives and another, more conservative cut-point that minimized false positives. Conclusion The CSBI as currently configured measures two different constructions and only the Control subscale is helpful in diagnosing CSB. We have, therefore, decided to eliminate the Violence subscale and move forward with a 13-item scale that we have named the CSBI-13. Two cut points were developed from this revised scale, one which is useful as a clinical screening and the other, more conservative measure useful for etiological and epidemiological research. PMID:28499521
VarBin, a novel method for classifying true and false positive variants in NGS data

PubMed Central

2013-01-01

Background Variant discovery for rare genetic diseases using Illumina genome or exome sequencing involves screening of up to millions of variants to find only the one or few causative variant(s). Sequencing or alignment errors create "false positive" variants, which are often retained in the variant screening process. Methods to remove false positive variants often retain many false positive variants. This report presents VarBin, a method to prioritize variants based on a false positive variant likelihood prediction. Methods VarBin uses the Genome Analysis Toolkit variant calling software to calculate the variant-to-wild type genotype likelihood ratio at each variant change and position divided by read depth. The resulting Phred-scaled, likelihood-ratio by depth (PLRD) was used to segregate variants into 4 Bins with Bin 1 variants most likely true and Bin 4 most likely false positive. PLRD values were calculated for a proband of interest and 41 additional Illumina HiSeq, exome and whole genome samples (proband's family or unrelated samples). At variant sites without apparent sequencing or alignment error, wild type/non-variant calls cluster near -3 PLRD and variant calls typically cluster above 10 PLRD. Sites with systematic variant calling problems (evident by variant quality scores and biases as well as displayed on the iGV viewer) tend to have higher and more variable wild type/non-variant PLRD values. Depending on the separation of a proband's variant PLRD value from the cluster of wild type/non-variant PLRD values for background samples at the same variant change and position, the VarBin method's classification is assigned to each proband variant (Bin 1 to Bin 4). Results To assess VarBin performance, Sanger sequencing was performed on 98 variants in the proband and background samples. True variants were confirmed in 97% of Bin 1 variants, 30% of Bin 2, and 0% of Bin 3/Bin 4. Conclusions These data indicate that VarBin correctly classifies the majority of true variants as Bin 1 and Bin 3/4 contained only false positive variants. The "uncertain" Bin 2 contained both true and false positive variants. Future work will further differentiate the variants in Bin 2. PMID:24266885
The impact of joint responses of devices in an airport security system.

PubMed

Nie, Xiaofeng; Batta, Rajan; Drury, Colin G; Lin, Li

2009-02-01

In this article, we consider a model for an airport security system in which the declaration of a threat is based on the joint responses of inspection devices. This is in contrast to the typical system in which each check station independently declares a passenger as having a threat or not having a threat. In our framework the declaration of threat/no-threat is based upon the passenger scores at the check stations he/she goes through. To do this we use concepts from classification theory in the field of multivariate statistics analysis and focus on the main objective of minimizing the expected cost of misclassification. The corresponding correct classification and misclassification probabilities can be obtained by using a simulation-based method. After computing the overall false alarm and false clear probabilities, we compare our joint response system with two other independently operated systems. A model that groups passengers in a manner that minimizes the false alarm probability while maintaining the false clear probability within specifications set by a security authority is considered. We also analyze the staffing needs at each check station for such an inspection scheme. An illustrative example is provided along with sensitivity analysis on key model parameters. A discussion is provided on some implementation issues, on the various assumptions made in the analysis, and on potential drawbacks of the approach.
Targeting the 5T4 oncofetal glycoprotein with an antibody drug conjugate (A1mcMMAF) improves survival in patient-derived xenograft models of acute lymphoblastic leukemia.

PubMed

McGinn, Owen J; Krishnan, Shekhar; Bourquin, Jean-Pierre; Sapra, Puja; Dempsey, Clare; Saha, Vaskar; Stern, Peter L

2017-06-01

Outcome in childhood acute lymphoblastic leukemia is prognosticated from levels of minimal residual disease after remission induction therapy. Higher levels of minimal residual disease are associated with inferior results even with intensification of therapy, thus suggesting that identification and targeting of minimal residual disease cells could be a therapeutic strategy. Here we identify high expression of 5T4 in subclonal populations of patient-derived xenografts from patients with high, post-induction levels of minimal residual disease. 5T4-positive cells showed preferential ability to overcome the NOD- scid IL2Rγ null mouse xenograft barrier, migrated in vitro on a CXCL12 gradient, preferentially localized to bone marrow in vivo and displayed the ability to reconstitute the original clonal composition on limited dilution engraftment. Treatment with A1mcMMAF (a 5T4-antibody drug conjugate) significantly improved survival without overt toxicity in mice engrafted with a 5T4-positive acute lymphoblastic leukemia cell line. Mice engrafted with 5T4-positive patient-derived xenograft cells were treated with combination chemotherapy or dexamethasone alone and then given A1mcMMAF in the minimal residual disease setting. Combination chemotherapy was toxic to NOD- scid IL2Rγ null mice. While dexamethasone or A1mcMMAF alone improved outcomes, the sequential administration of dexamethasone and A1mcMMAF significantly improved survival ( P =0.0006) over either monotherapy. These data show that specifically targeting minimal residual disease cells improved outcomes and support further investigation of A1mcMMAF in patients with high-risk B-cell precursor acute lymphoblastic leukemia identified by 5T4 expression at diagnosis. Copyright© Ferrata Storti Foundation.
Targeting the 5T4 oncofetal glycoprotein with an antibody drug conjugate (A1mcMMAF) improves survival in patient-derived xenograft models of acute lymphoblastic leukemia

PubMed Central

McGinn, Owen J.; Krishnan, Shekhar; Bourquin, Jean-Pierre; Sapra, Puja; Dempsey, Clare; Saha, Vaskar; Stern, Peter L.

2017-01-01

Outcome in childhood acute lymphoblastic leukemia is prognosticated from levels of minimal residual disease after remission induction therapy. Higher levels of minimal residual disease are associated with inferior results even with intensification of therapy, thus suggesting that identification and targeting of minimal residual disease cells could be a therapeutic strategy. Here we identify high expression of 5T4 in subclonal populations of patient-derived xenografts from patients with high, post-induction levels of minimal residual disease. 5T4-positive cells showed preferential ability to overcome the NOD-scidIL2Rγnull mouse xenograft barrier, migrated in vitro on a CXCL12 gradient, preferentially localized to bone marrow in vivo and displayed the ability to reconstitute the original clonal composition on limited dilution engraftment. Treatment with A1mcMMAF (a 5T4-antibody drug conjugate) significantly improved survival without overt toxicity in mice engrafted with a 5T4-positive acute lymphoblastic leukemia cell line. Mice engrafted with 5T4-positive patient-derived xenograft cells were treated with combination chemotherapy or dexamethasone alone and then given A1mcMMAF in the minimal residual disease setting. Combination chemotherapy was toxic to NOD-scidIL2Rγnull mice. While dexamethasone or A1mcMMAF alone improved outcomes, the sequential administration of dexamethasone and A1mcMMAF significantly improved survival (P=0.0006) over either monotherapy. These data show that specifically targeting minimal residual disease cells improved outcomes and support further investigation of A1mcMMAF in patients with high-risk B-cell precursor acute lymphoblastic leukemia identified by 5T4 expression at diagnosis. PMID:28341731
Misdiagnosis of HIV infection during a South African community-based survey: implications for rapid HIV testing

PubMed Central

Kufa, Tendesayi; Kharsany, Ayesha BM; Cawood, Cherie; Khanyile, David; Lewis, Lara; Grobler, Anneke; Chipeta, Zawadi; Bere, Alfred; Glenshaw, Mary; Puren, Adrian

2017-01-01

Abstract Introduction: We describe the overall accuracy and performance of a serial rapid HIV testing algorithm used in community-based HIV testing in the context of a population-based household survey conducted in two sub-districts of uMgungundlovu district, KwaZulu-Natal, South Africa, against reference fourth-generation HIV-1/2 antibody and p24 antigen combination immunoassays. We discuss implications of the findings on rapid HIV testing programmes. Methods: Cross-sectional design: Following enrolment into the survey, questionnaires were administered to eligible and consenting participants in order to obtain demographic and HIV-related data. Peripheral blood samples were collected for HIV-related testing. Participants were offered community-based HIV testing in the home by trained field workers using a serial algorithm with two rapid diagnostic tests (RDTs) in series. In the laboratory, reference HIV testing was conducted using two fourth-generation immunoassays with all positives in the confirmatory test considered true positives. Accuracy, sensitivity, specificity, positive predictive value, negative predictive value and false-positive and false-negative rates were determined. Results: Of 10,236 individuals enrolled in the survey, 3740 were tested in the home (median age 24 years (interquartile range 19–31 years), 42.1% males and HIV positivity on RDT algorithm 8.0%). From those tested, 3729 (99.7%) had a definitive RDT result as well as a laboratory immunoassay result. The overall accuracy of the RDT when compared to the fourth-generation immunoassays was 98.8% (95% confidence interval (CI) 98.5–99.2). The sensitivity, specificity, positive predictive value and negative predictive value were 91.1% (95% CI 87.5–93.7), 99.9% (95% CI 99.8–100), 99.3% (95% CI 97.4–99.8) and 99.1% (95% CI 98.8–99.4) respectively. The false-positive and false-negative rates were 0.06% (95% CI 0.01–0.24) and 8.9% (95% CI 6.3–12.53). Compared to true positives, false negatives were more likely to be recently infected on limited antigen avidity assay and to report antiretroviral therapy (ART) use. Conclusions: The overall accuracy of the RDT algorithm was high. However, there were few false positives, and the sensitivity was lower than expected with high false negatives, despite implementation of quality assurance measures. False negatives were associated with recent (early) infection and ART exposure. The RDT algorithm was able to correctly identify the majority of HIV infections in community-based HIV testing. Messaging on the potential for false positives and false negatives should be included in these programmes. PMID:28872274
Affective valence influences participant's susceptibility to false memories and illusory recollection.

PubMed

Dehon, Hedwige; Larøi, Frank; Van der Linden, Martial

2010-10-01

This study examined the influence of emotional valence on the production of DRM false memories (Roediger & McDermott, 1995). Participants were presented with neutral, positive, or negative DRM lists for a later recognition (Experiment 1) or recall (Experiment 2) test. In both experiments, confidence and recollective experience (i.e., "Remember-Know" judgments; Tulving, 1985) were also assessed. Results consistently showed that, compared with neutral lists, affective lists induced more false recognition and recall of nonpresented critical lures. Moreover, although confidence ratings did not differ between the false remembering from the different kinds of lists, "Remember" responses were more often associated with negative than positive and neutral false remembering of the critical lures. In contrast, positive false remembering of the critical lures was more often associated with "Know" responses. These results are discussed in light of the Paradoxical Negative Emotion (PNE) hypothesis (Porter, Taylor, & ten Bricke, 2008). (PsycINFO Database Record (c) 2010 APA, all rights reserved).
Hair Follicle Bulb as a Biodosimeter for Low-Level VX Vapor Exposure: Initial Studies Validating the Presence of Potential Protein Biomarkers of Exposure in the Sprague-Dawley Rat Whisker Follicle

DTIC Science & Technology

2006-10-01

lead to false positive segmental hair analysis results.13 Due to the increased risk of false positives associated with segmental hair analysis ...to 200 mg of hair (to allow confirmation testing). 7 The segments are typically washed to remove external contaminants and the chemicals in the hair ...further confirmation. The method overcomes the false positives associated with traditional segmental hair analysis such. By measuring the
Early Disseminated Lyme Disease Causing False-Positive Serology for Primary Epstein-Barr Virus Infection: Report of 2 Cases.

PubMed

Pavletic, Adriana J; Marques, Adriana R

2017-07-15

False-positive serology for Lyme disease was reported in patients with acute infectious mononucleosis. Here we describe 2 patients with early disseminated Lyme disease who were misdiagnosed with infectious mononucleosis based on false-positive tests for primary Epstein-Barr virus infection. Published by Oxford University Press for the Infectious Diseases Society of America 2017. This work is written by (a) US Government employee(s) and is in the public domain in the US.
Comparing Recalibration Strategies for Electroencephalography-Based Decoders of Movement Intention in Neurological Patients with Motor Disability.

PubMed

López-Larraz, Eduardo; Ibáñez, Jaime; Trincado-Alonso, Fernando; Monge-Pereira, Esther; Pons, José Luis; Montesano, Luis

2017-12-17

Motor rehabilitation based on the association of electroencephalographic (EEG) activity and proprioceptive feedback has been demonstrated as a feasible therapy for patients with paralysis. To promote long-lasting motor recovery, these interventions have to be carried out across several weeks or even months. The success of these therapies partly relies on the performance of the system decoding movement intentions, which normally has to be recalibrated to deal with the nonstationarities of the cortical activity. Minimizing the recalibration times is important to reduce the setup preparation and maximize the effective therapy time. To date, a systematic analysis of the effect of recalibration strategies in EEG-driven interfaces for motor rehabilitation has not yet been performed. Data from patients with stroke (4 patients, 8 sessions) and spinal cord injury (SCI) (4 patients, 5 sessions) undergoing two different paradigms (self-paced and cue-guided, respectively) are used to study the performance of the EEG-based classification of motor intentions. Four calibration schemes are compared, considering different combinations of training datasets from previous and/or the validated session. The results show significant differences in classifier performances in terms of the true and false positives (TPs) and (FPs). Combining training data from previous sessions with data from the validation session provides the best compromise between the amount of data needed for calibration and the classifier performance. With this scheme, the average true (false) positive rates obtained are 85.3% (17.3%) and 72.9% (30.3%) for the self-paced and the cue-guided protocols, respectively. These results suggest that the use of optimal recalibration schemes for EEG-based classifiers of motor intentions leads to enhanced performances of these technologies, while not requiring long calibration phases prior to starting the intervention.
Perils of using speed zone data to assess real-world compliance to speed limits.

PubMed

Chevalier, Anna; Clarke, Elizabeth; Chevalier, Aran John; Brown, Julie; Coxon, Kristy; Ivers, Rebecca; Keay, Lisa

2017-11-17

Real-world driving studies, including those involving speeding alert devices and autonomous vehicles, can gauge an individual vehicle's speeding behavior by comparing measured speed with mapped speed zone data. However, there are complexities with developing and maintaining a database of mapped speed zones over a large geographic area that may lead to inaccuracies within the data set. When this approach is applied to large-scale real-world driving data or speeding alert device data to determine speeding behavior, these inaccuracies may result in invalid identification of speeding. We investigated speeding events based on service provider speed zone data. We compared service provider speed zone data (Speed Alert by Smart Car Technologies Pty Ltd., Ultimo, NSW, Australia) against a second set of speed zone data (Google Maps Application Programming Interface [API] mapped speed zones). We found a systematic error in the zones where speed limits of 50-60 km/h, typical of local roads, were allocated to high-speed motorways, which produced false speed limits in the speed zone database. The result was detection of false-positive high-range speeding. Through comparison of the service provider speed zone data against a second set of speed zone data, we were able to identify and eliminate data most affected by this systematic error, thereby establishing a data set of speeding events with a high level of sensitivity (a true positive rate of 92% or 6,412/6,960). Mapped speed zones can be a source of error in real-world driving when examining vehicle speed. We explored the types of inaccuracies found within speed zone data and recommend that a second set of speed zone data be utilized when investigating speeding behavior or developing mapped speed zone data to minimize inaccuracy in estimates of speeding.
Colorimetric detection with aptamer-gold nanoparticle conjugates coupled to an android-based color analysis application for use in the field.

PubMed

Smith, Joshua E; Griffin, Daniel K; Leny, Juliann K; Hagen, Joshua A; Chávez, Jorge L; Kelley-Loughnane, Nancy

2014-04-01

The feasibility of using aptamer-gold nanoparticle conjugates (Apt-AuNPs) to design colorimetric assays for in the field detection of small molecules was investigated. An assay to detect cocaine was designed using two clones of a known cocaine-binding aptamer. The assay was based on the AuNPs difference in affinity for single-stranded DNA (non-binding) and double stranded DNA (target bound). In the first assay, a commonly used design was followed, in which the aptamer and target were incubated to allow binding followed by exposure to the AuNPs. Interactions between the non-bound analytes and the AuNPs surface resulted in a number of false positives. The assay was redesigned by incubating the AuNPs and the aptamer prior to target addition to passivate the AuNPs surface. The adsorbed aptamer was able to bind the target while preventing non-specific interactions. The assay was validated with a number of masking and cutting agents and other controlled substances showing minimal false positives. Studies to improve the assay performance in the field were performed, showing that assay activity could be preserved for up to 2 months. To facilitate the assay analysis, an android application for automatic colorimetric characterization was developed. The application was validated by challenging the assay with cocaine standards of different concentrations, and comparing the results to a conventional plate reader, showing outstanding agreement. Finally, the rapid identification of cocaine in mixtures mimicking street samples was demonstrated. This work established that Apt-AuNPs can be used to design robust assays to be used in the field. Copyright © 2013 Elsevier B.V. All rights reserved.

Usefulness of a single item in a mail survey to identify persons with possible dementia: a new strategy for finding high-risk elders.

PubMed

Brody, Kathleen K; Maslow, Katie; Perrin, Nancy A; Crooks, Valerie; DellaPenna, Richard; Kuang, Daniel

2005-04-01

The objective of this study was to examine the characteristics of elderly persons who responded positively to a question about "severe memory problems" on a mailed health questionnaire yet were missed by the existing health risk algorithm to identify vulnerable elderly persons. A total of 324,471 respondents aged 65 and older completed a primary care health status questionnaire that gathered clinical information to quickly identify members with functional impairment, multiple chronic diseases, and higher medical care needs. The respondents were part of a large, integrated, not-for-profit managed care organization that implemented a model of care for elders using a uniform risk identification method across eight regions. Respondents with severe memory problems were compared to general respondents by morbidity, geriatric syndromes, functional impairments, service utilization, sensory impairments, sociodemographic characteristics, and activities of daily living. Of the respondents, 13,902 persons (4.3%) reported severe memory problems; the existing health risk algorithm missed 47.1% of these. When severe memory problems were included in the risk algorithm, identification increased from 11% to 13%, and risk prevalence by age groups ranged from 4.4% to 40.5%; one third had severe memory problems, a finding that was fairly consistent within age groups (28.4% to 36.5%). A question about severe memory problems should be incorporated into population risk-identification techniques. While false-negative rates are unknown, the false-positive rate of a self-report mail survey appears to be minimal. Persons reporting severe memory problems clearly have multiple comorbidities, higher prevalence of geriatric syndromes, and greater functional and sensory impairments.
Application of neuro-fuzzy methods to gamma spectroscopy

NASA Astrophysics Data System (ADS)

Grelle, Austin L.

Nuclear non-proliferation activities are an essential part of national security activities both domestic and abroad. The safety of the public in densely populated environments such as urban areas or large events can be compromised if devices using special nuclear materials are present. Therefore, the prompt and accurate detection of these materials is an important topic of research, in which the identification of normal conditions is also of importance. With gamma-ray spectroscopy, these conditions are identified as the radiation background, which though being affected by a multitude of factors is ever present. Therefore, in nuclear non-proliferation activities the accurate identification of background is important. With this in mind, a method has been developed to utilize aggregate background data to predict the background of a location through the use of an Artificial Neural Network (ANN). After being trained on background data, the ANN is presented with nearby relevant gamma-ray spectroscopy data---as identified by a Fuzzy Inference System - to create a predicted background spectra to compare to a measured spectra. If a significant deviation exists between the predicted and measured data, the method alerts the user such that a more thorough investigation can take place. Research herein focused on data from an urban setting in which the number of false positives was observed to be 28 out of a total of 987, representing 2.94% error. The method therefore currently shows a high rate of false positives given the current configuration, however there are promising steps that can be taken to further minimize this error. With this in mind, the method stands as a potentially significant tool in urban nuclear nonproliferation activities.
Prediction of clinical infection in women with preterm labour with intact membranes: a score based on ultrasonographic, clinical and biological markers.

PubMed

Kayem, Gilles; Maillard, Françoise; Schmitz, Thomas; Jarreau, Pierre H; Cabrol, Dominique; Breart, Gérard; Goffinet, François

2009-07-01

To predict maternal and neonatal clinical infection at admission in women hospitalized for preterm labour (PTL) with intact membranes. Prospective study of 371 women hospitalized for preterm labour with intact membranes. The primary outcome was clinical infection, defined by clinical chorioamnionitis at delivery or early-onset neonatal infection. Clinical infection was identified in 21 cases (5.7%) and was associated with earlier gestational age at admission for PTL, elevated maternal C-reactive protein (CRP) and white blood cell count (WBC), shorter cervical length, and a cervical funnelling on ultrasound. We used ROC curves to determine the cut-off values that minimized the number of false positives and false negatives. The cut-off points chosen were 30 weeks for gestational age at admission, 25 mm for cervical length, 8 mg/l for CRP and 12,000 c/mm(3) for WBC. Each of these variables was assigned a weight on the basis of the adjusted odds ratios in a clinical infection risk score (CIRS). We set a threshold corresponding to a specificity close to 90%, and calculated the positive and negative predictive values and likelihood ratios of each marker and of the CIRS. The CIRS had a sensitivity of 61.9%, while the sensitivity of the other markers ranged from 19.0% to 42.9%. Internal cross-validation was used to estimate the performance of the CIRS in new subjects. The diagnostic values found remained close to the initial values. A clinical infection risk score built from data known at admission for preterm labour helps to identify women and newborns at high risk of clinical infection.
Statistics provide guidance for indigenous organic carbon detection on Mars missions.

PubMed

Sephton, Mark A; Carter, Jonathan N

2014-08-01

Data from the Viking and Mars Science Laboratory missions indicate the presence of organic compounds that are not definitively martian in origin. Both contamination and confounding mineralogies have been suggested as alternatives to indigenous organic carbon. Intuitive thought suggests that we are repeatedly obtaining data that confirms the same level of uncertainty. Bayesian statistics may suggest otherwise. If an organic detection method has a true positive to false positive ratio greater than one, then repeated organic matter detection progressively increases the probability of indigeneity. Bayesian statistics also reveal that methods with higher ratios of true positives to false positives give higher overall probabilities and that detection of organic matter in a sample with a higher prior probability of indigenous organic carbon produces greater confidence. Bayesian statistics, therefore, provide guidance for the planning and operation of organic carbon detection activities on Mars. Suggestions for future organic carbon detection missions and instruments are as follows: (i) On Earth, instruments should be tested with analog samples of known organic content to determine their true positive to false positive ratios. (ii) On the mission, for an instrument with a true positive to false positive ratio above one, it should be recognized that each positive detection of organic carbon will result in a progressive increase in the probability of indigenous organic carbon being present; repeated measurements, therefore, can overcome some of the deficiencies of a less-than-definitive test. (iii) For a fixed number of analyses, the highest true positive to false positive ratio method or instrument will provide the greatest probability that indigenous organic carbon is present. (iv) On Mars, analyses should concentrate on samples with highest prior probability of indigenous organic carbon; intuitive desires to contrast samples of high prior probability and low prior probability of indigenous organic carbon should be resisted.
Determining the Minimal Required Radioactivity of 18F-FDG for Reliable Semiquantification in PET/CT Imaging: A Phantom Study.

PubMed

Chen, Ming-Kai; Menard, David H; Cheng, David W

2016-03-01

In pursuit of as-low-as-reasonably-achievable (ALARA) doses, this study investigated the minimal required radioactivity and corresponding imaging time for reliable semiquantification in PET/CT imaging. Using a phantom containing spheres of various diameters (3.4, 2.1, 1.5, 1.2, and 1.0 cm) filled with a fixed (18)F-FDG concentration of 165 kBq/mL and a background concentration of 23.3 kBq/mL, we performed PET/CT at multiple time points over 20 h of radioactive decay. The images were acquired for 10 min at a single bed position for each of 10 half-lives of decay using 3-dimensional list mode and were reconstructed into 1-, 2-, 3-, 4-, 5-, and 10-min acquisitions per bed position using an ordered-subsets expectation maximum algorithm with 24 subsets and 2 iterations and a gaussian 2-mm filter. SUVmax and SUVavg were measured for each sphere. The minimal required activity (±10%) for precise SUVmax semiquantification in the spheres was 1.8 kBq/mL for an acquisition of 10 min, 3.7 kBq/mL for 3-5 min, 7.9 kBq/mL for 2 min, and 17.4 kBq/mL for 1 min. The minimal required activity concentration-acquisition time product per bed position was 10-15 kBq/mL⋅min for reproducible SUV measurements within the spheres without overestimation. Using the total radioactivity and counting rate from the entire phantom, we found that the minimal required total activity-time product was 17 MBq⋅min and the minimal required counting rate-time product was 100 kcps⋅min. Our phantom study determined a threshold for minimal radioactivity and acquisition time for precise semiquantification in (18)F-FDG PET imaging that can serve as a guide in pursuit of achieving ALARA doses. © 2016 by the Society of Nuclear Medicine and Molecular Imaging, Inc.
Young Adolescents' Responses to Positive Events: Associations with Positive Affect and Adjustment

ERIC Educational Resources Information Center

Gentzler, Amy L.; Morey, Jennifer N.; Palmer, Cara A.; Yi, Chit Yuen

2013-01-01

This study examined how maximizing and minimizing responses to positive events were associated with sustained positive feelings about the events and adjustment in a community sample of 56 young adolescents (31 boys and 25 girls, 10-14 years of age). On daily reports, adolescents reported their positive emotional reactions to their best event each…
Development of a Test Facility for Air Revitalization Technology Evaluation

NASA Technical Reports Server (NTRS)

Lu, Sao-Dung; Lin, Amy; Campbell, Melissa; Smith, Frederick

2006-01-01

An active fault tolerant control (FTC) law is generally sensitive to false identification since the control gain is reconfigured for fault occurrence. In the conventional FTC law design procedure, dynamic variations due to false identification are not considered. In this paper, an FTC synthesis method is developed in order to consider possible variations of closed-loop dynamics under false identification into the control design procedure. An active FTC synthesis problem is formulated into an LMI optimization problem to minimize the upper bound of the induced-L2 norm which can represent the worst-case performance degradation due to false identification. The developed synthesis method is applied for control of the longitudinal motions of FASER (Free-flying Airplane for Subscale Experimental Research). The designed FTC law of the airplane is simulated for pitch angle command tracking under a false identification case.
Positive events protect children from causal false memories for scripted events.

PubMed

Melinder, Annika; Toffalini, Enrico; Geccherle, Eleonora; Cornoldi, Cesare

2017-11-01

Adults produce fewer inferential false memories for scripted events when their conclusions are emotionally charged than when they are neutral, but it is not clear whether the same effect is also found in children. In the present study, we examined this issue in a sample of 132 children aged 6-12 years (mean 9 years, 3 months). Participants encoded photographs depicting six script-like events that had a positively, negatively, or a neutral valenced ending. Subsequently, true and false recognition memory of photographs related to the observed scripts was tested as a function of emotionality. Causal errors-a type of false memory thought to stem from inferential processes-were found to be affected by valence: children made fewer causal errors for positive than for neutral or negative events. Hypotheses are proposed on why adults were found protected against inferential false memories not only by positive (as for children) but also by negative endings when administered similar versions of the same paradigm.
Minimal Invasive Left Ventricular Lead Repositioning is Safe and Effective in Distal Left Ventricular Lead Positions.

PubMed

Osztheimer, István; Szilágyi, Szabolcs; Pongor, Zsuzsanna; Zima, Endre; Molnár, Levente; Tahin, Tamás; Merkely, Béla; Gellér, László

2017-05-01

Treatment of left ventricular electrode dislocation and phrenic nerve stimulation remains an issue in the era of new electrode designs. Safety and efficacy of minimal invasive lead repositioning and pocket opening reposition procedures were evaluated between December 2005 and December 2012 at our center. Minimal invasive method was developed and widely utilized at our center to treat phrenic nerve stimulation. The distally positioned left ventricular lead is looped around by a deflectable catheter in the right atrium introduced from the femoral vein access and then pulled back. Coronary stent implantation was used afterwards for lead stabilization in some patients. 42 minimal invasive and 48 electrode repositions with pacemaker pocket opening were performed at 77 patients for left ventricular lead problems. Minimal invasive reposition could be carried out successfully in 69% of (29 patients) cases. Note that in 14.3% of the cases (six patients) minimal invasive procedures were acutely unsuccessful and crossover was necessary. In 16.6% of the cases (seven patients) lead issues were noted later during follow-up. Opening of the pocket could be carried out successfully in 81.2% (39 patients) and was unsuccessful acutely in 6.25% (three patients). Repeated dislocation was noticed, 12.5%, in this group (six patients). Complication during minimal invasive procedures was electrode injury in one case. Pocket openings were associated with several complications: atrial fibrillation, pericardial effusion, fever, hematoma, and right ventricular electrode dislodgement. Minimal invasive procedure-as the first line approach-is safe and feasible for left ventricular electrode repositioning in selected cases. © 2017 Wiley Periodicals, Inc.
On complexity of trellis structure of linear block codes

NASA Technical Reports Server (NTRS)

Lin, Shu

1990-01-01

The trellis structure of linear block codes (LBCs) is discussed. The state and branch complexities of a trellis diagram (TD) for a LBC is investigated. The TD with the minimum number of states is said to be minimal. The branch complexity of a minimal TD for a LBC is expressed in terms of the dimensions of specific subcodes of the given code. Then upper and lower bounds are derived on the number of states of a minimal TD for a LBC, and it is shown that a cyclic (or shortened cyclic) code is the worst in terms of the state complexity among the LBCs of the same length and dimension. Furthermore, it is shown that the structural complexity of a minimal TD for a LBC depends on the order of its bit positions. This fact suggests that an appropriate permutation of the bit positions of a code may result in an equivalent code with a much simpler minimal TD. Boolean polynomial representation of codewords of a LBC is also considered. This representation helps in study of the trellis structure of the code. Boolean polynomial representation of a code is applied to construct its minimal TD. Particularly, the construction of minimal trellises for Reed-Muller codes and the extended and permuted binary primitive BCH codes which contain Reed-Muller as subcodes is emphasized. Finally, the structural complexity of minimal trellises for the extended and permuted, and double-error-correcting BCH codes is analyzed and presented. It is shown that these codes have relatively simple trellis structure and hence can be decoded with the Viterbi decoding algorithm.
Optimal Sensor Location Design for Reliable Fault Detection in Presence of False Alarms

PubMed Central

Yang, Fan; Xiao, Deyun; Shah, Sirish L.

2009-01-01

To improve fault detection reliability, sensor location should be designed according to an optimization criterion with constraints imposed by issues of detectability and identifiability. Reliability requires the minimization of undetectability and false alarm probability due to random factors on sensor readings, which is not only related with sensor readings but also affected by fault propagation. This paper introduces the reliability criteria expression based on the missed/false alarm probability of each sensor and system topology or connectivity derived from the directed graph. The algorithm for the optimization problem is presented as a heuristic procedure. Finally, a boiler system is illustrated using the proposed method. PMID:22291524
False-positive rate determination of protein target discovery using a covalent modification- and mass spectrometry-based proteomics platform.

PubMed

Strickland, Erin C; Geer, M Ariel; Hong, Jiyong; Fitzgerald, Michael C

2014-01-01

Detection and quantitation of protein-ligand binding interactions is important in many areas of biological research. Stability of proteins from rates of oxidation (SPROX) is an energetics-based technique for identifying the proteins targets of ligands in complex biological mixtures. Knowing the false-positive rate of protein target discovery in proteome-wide SPROX experiments is important for the correct interpretation of results. Reported here are the results of a control SPROX experiment in which chemical denaturation data is obtained on the proteins in two samples that originated from the same yeast lysate, as would be done in a typical SPROX experiment except that one sample would be spiked with the test ligand. False-positive rates of 1.2-2.2% and <0.8% are calculated for SPROX experiments using Q-TOF and Orbitrap mass spectrometer systems, respectively. Our results indicate that the false-positive rate is largely determined by random errors associated with the mass spectral analysis of the isobaric mass tag (e.g., iTRAQ®) reporter ions used for peptide quantitation. Our results also suggest that technical replicates can be used to effectively eliminate such false positives that result from this random error, as is demonstrated in a SPROX experiment to identify yeast protein targets of the drug, manassantin A. The impact of ion purity in the tandem mass spectral analyses and of background oxidation on the false-positive rate of protein target discovery using SPROX is also discussed.
An Evaluation of Unit and ½ Mass Correction Approaches as a ...

EPA Pesticide Factsheets

Rare earth elements (REE) and certain alkaline earths can produce M+2 interferences in ICP-MS because they have sufficiently low second ionization energies. Four REEs (150Sm, 150Nd, 156Gd and 156Dy) produce false positives on 75As and 78Se and 132Ba can produce a false positive on 66Zn. Currently, US EPA Method 200.8 does not address these as sources of false positives. Additionally, these M+2 false positives are typically enhanced if collision cell technology is utilized to reduce polyatomic interferences associated with ICP-MS detection. A preliminary evaluation indicates that instrumental tuning conditions can impact the observed M+2/M+1 ratio and in turn the false positives generated on Zn, As and Se. Both unit and ½ mass approaches will be evaluated to correct for these false positives relative to the benchmark concentrations estimates from a triple quadrupole ICP-MS using standard solutions. The impact of matrix on these M+2 corrections will be evaluated over multiple analysis days with a focus on evaluating internal standards that mirror the matrix induced shifts in the M+2 ion transmission. The goal of this evaluation is to move away from fixed M+2 corrective approaches and move towards sample specific approaches that mimic the sample matrix induced variability while attempting to address intra-day variability of the M+2 correction factors through the use of internal standards. Oral Presentation via webinar for EPA Laboratory Technical Informati
Quality control in the diagnosis of Trichuris trichiura and Ascaris lumbricoides using the Kato-Katz technique: experience from three randomised controlled trials.

PubMed

Speich, Benjamin; Ali, Said M; Ame, Shaali M; Albonico, Marco; Utzinger, Jürg; Keiser, Jennifer

2015-02-05

An accurate diagnosis of soil-transmitted helminthiasis is important for individual patient management, for drug efficacy evaluation and for monitoring control programmes. The Kato-Katz technique is the most widely used method detecting soil-transmitted helminth eggs in faecal samples. However, detailed analyses of quality control, including false-positive and faecal egg count (FEC) estimates, have received little attention. Over a 3-year period, within the frame of a series of randomised controlled trials conducted in Pemba, United Republic of Tanzania, 10% of randomly selected Kato-Katz thick smears were re-read for Trichuris trichiura and Ascaris lumbricoides eggs. In case of discordant result (i.e. positive versus negative) the slides were re-examined a third time. A result was assumed to be false-positive or false-negative if the result from the initial reading did not agree with the quality control as well as the third reading. We also evaluated the general agreement in FECs between the first and second reading, according to internal and World Health Organization (WHO) guidelines. From the 1,445 Kato-Katz thick smears subjected to quality control, 1,181 (81.7%) were positive for T. trichiura and 290 (20.1%) were positive for A. lumbricoides. During quality control, very low rates of false-positive results were observed; 0.35% (n = 5) for T. trichiura and 0.28% (n = 4) for A. lumbricoides. False-negative readings of Kato-Katz thick smears were obtained in 28 (1.94%) and 6 (0.42%) instances for T. trichiura and A. lumbricoides, respectively. A high frequency of discordant results in FECs was observed (i.e. 10.0-23.9% for T. trichiura, and 9.0-11.4% for A. lumbricoides). Our analyses show that the rate of false-positive diagnoses of soil-transmitted helminths is low. As the probability of false-positive results increases after examination of multiple stool samples from a single individual, the potential influence of false-positive results on epidemiological studies and anthelminthic drug efficacy studies should be determined. Existing WHO guidelines for quality control might be overambitious and might have to be revised, specifically with regard to handling disagreements in FECs.
Evaluating Alerting and Guidance Performance of a UAS Detect-And-Avoid System

NASA Technical Reports Server (NTRS)

Lee, Seung Man; Park, Chunki; Thipphavong, David P.; Isaacson, Douglas R.; Santiago, Confesor

2016-01-01

A key challenge to the routine, safe operation of unmanned aircraft systems (UAS) is the development of detect-and-avoid (DAA) systems to aid the UAS pilot in remaining "well clear" of nearby aircraft. The goal of this study is to investigate the effect of alerting criteria and pilot response delay on the safety and performance of UAS DAA systems in the context of routine civil UAS operations in the National Airspace System (NAS). A NAS-wide fast-time simulation study was conducted to assess UAS DAA system performance with a large number of encounters and a broad set of DAA alerting and guidance system parameters. Three attributes of the DAA system were controlled as independent variables in the study to conduct trade-off analyses: UAS trajectory prediction method (dead-reckoning vs. intent-based), alerting time threshold (related to predicted time to LoWC), and alerting distance threshold (related to predicted Horizontal Miss Distance, or HMD). A set of metrics, such as the percentage of true positive, false positive, and missed alerts, based on signal detection theory and analysis methods utilizing the Receiver Operating Characteristic (ROC) curves were proposed to evaluate the safety and performance of DAA alerting and guidance systems and aid development of DAA system performance standards. The effect of pilot response delay on the performance of DAA systems was evaluated using a DAA alerting and guidance model and a pilot model developed to support this study. A total of 18 fast-time simulations were conducted with nine different DAA alerting threshold settings and two different trajectory prediction methods, using recorded radar traffic from current Visual Flight Rules (VFR) operations, and supplemented with DAA-equipped UAS traffic based on mission profiles modeling future UAS operations. Results indicate DAA alerting distance threshold has a greater effect on DAA system performance than DAA alerting time threshold or ownship trajectory prediction method. Further analysis on the alert lead time (time in advance of predicted loss of well clear at which a DAA alert is first issued) indicated a strong positive correlation between alert lead time and DAA system performance (i.e. the ability of the UAS pilot to maneuver the unmanned aircraft to remain well clear). While bigger distance thresholds had beneficial effects on alert lead time and missed alert rate, it also generated a higher rate of false alerts. In the design and development of DAA alerting and guidance systems, therefore, the positive and negative effects of false alerts and missed alerts should be carefully considered to achieve acceptable alerting system performance by balancing false and missed alerts. The results and methodology presented in this study are expected to help stakeholders, policymakers and standards committees define the appropriate setting of DAA system parameter thresholds for UAS that ensure safety while minimizing operational impacts to the NAS and equipage requirements for its users before DAA operational performance standards can be finalized.
Complex Recanalization of Chronic Total Occluison Supported by Minimal Extracorporeal Circulation in a Patient with an Aortic Valve Bioprothesis in Extraanatomic Position

PubMed Central

Jansen, Ruben; Bathgate, Brigitte; Bufe, Alexander

2018-01-01

Percutaneous coronary intervention (PCI) of chronic total occlusion (CTO) still remains a major challenge in interventional cardiology. This case describes a complex PCI of the left main coronary artery and of a CTO of the right coronary artery using a minimal extracorporeal circulation system (MECC) in a patient with an aortic valve bioprothesis in extraanatomic position. It illustrates that complex recanalization strategies can be solved combining it with mechanical circulatory support technologies. PMID:29850264
Extended focused assessment with sonography for trauma (EFAST) in the diagnosis of pneumothorax: experience at a community based level I trauma center.

PubMed

Nandipati, Kalyana C; Allamaneni, Shyam; Kakarla, Ravindra; Wong, Alfredo; Richards, Neil; Satterfield, James; Turner, James W; Sung, Kae-Jae

2011-05-01

Early identification of pneumothorax is crucial to reduce the mortality in critically injured patients. The objective of our study is to investigate the utility of surgeon performed extended focused assessment with sonography for trauma (EFAST) in the diagnosis of pneumothorax. We prospectively analysed 204 trauma patients in our level I trauma center over a period of 12 (06/2007-05/2008) months in whom EFAST was performed. The patients' demographics, type of injury, clinical examination findings (decreased air entry), CXR, EFAST and CT scan findings were entered into the data base. Sensitivity, specificity, positive (PPV) and negative predictive values (NPV) were calculated. Of 204 patients (mean age--43.01+/-19.5 years, sex--male 152, female 52) 21 (10.3%) patients had pneumothorax. Of 21 patients who had pneumothorax 12 were due to blunt trauma and 9 were due to penetrating trauma. The diagnosis of pneumothorax in 204 patients demonstrated the following: clinical examination was positive in 17 patients (true positive in 13/21, 62%; 4 were false positive and 8 were false negative), CXR was positive in 16 (true positive in 15/19, 79%; 1 false positive, 4 missed and 2 CXR not performed before chest tube) patients and EFAST was positive in 21 patients (20 were true positive [95.2%], 1 false positive and 1 false negative). In diagnosing pneumothorax EFAST has significantly higher sensitivity compared to the CXR (P=0.02). Surgeon performed trauma room extended FAST is simple and has higher sensitivity compared to the chest X-ray and clinical examination in detecting pneumothorax. Published by Elsevier Ltd.
When good news is bad news: psychological impact of false positive diagnosis of HIV.

PubMed

Bhattacharya, Rahul; Barton, Simon; Catalan, Jose

2008-05-01

HIV testing is known to be stressful, however the impact of false positive HIV results on individuals is not well documented. This is a series of four case who developed psychological difficulties and psychiatric morbidities after being informed they had been misdiagnosed with HIV-positive status. We look into documented cases of misdiagnosis and potential risks of misdiagnosis. The case series highlights the implications a false diagnosis HIV-positive status can have, even when the diagnosis is rectified. Impact of misdiagnosis of HIV can lead to psychosocial difficulties and psychiatric morbidity, have public health and epidemiological implications and can lead to medico-legal conflict. This further reiterates the importance of HIV testing carried out ethically and sensitively, and in line with guidelines, respecting confidentiality and consent, and offering counselling pre-test and post-test, being mindful of the reality of erroneous and false positive HIV test results. The implications of misdiagnosis are for the individual, their partners and social contacts, as well as for the community.
Comparison of different patient positioning strategies to minimize shoulder girdle artifacts in head and neck CT.

PubMed

Wirth, Stefan; Meindl, Thomas; Treitl, Marcus; Pfeifer, Klaus-Jürgen; Reiser, Maximilian

2006-08-01

The purpose of this study was to analyze different patient positioning strategies for minimizing artifacts of the shoulder girdle in head and neck CT. Standardized CT examinations of three positioning groups were compared (P: patients pushed their shoulders downwards; D: similar optimization by a pulling device; N: no particular positioning optimization). Parameters analyzed were the length of the cervical spine not being superimposed by the shoulder girdle as well as noise in the supraclavicular space. In groups P and D, the portion of the cervical spine not superimposed was significantly larger than in group N (P: 10.4 cm; D: 10.6 cm; N: 8.5 cm). At the supraclavicular space, noise decreased significantly (P: 12.5 HU; D: 12.1 HU; N: 17.7 HU). No significant differences between the two position-optimized groups (P and D) were detected. Optimized shoulder positioning by the patient increases image quality in CT head and neck imaging. The use of a pulling device offers no additional advantages.
False-positive iodine-131 whole-body scan findings in patients with differentiated thyroid carcinoma: report of 11 cases and review of the literature.

PubMed

Buton, Leckzinscka; Morel, Olivier; Gault, Patricia; Illouz, Frédéric; Rodien, Patrice; Rohmer, Vincent

2013-07-01

Iodine-131 (I-131) whole-body scan (WBS) plays an important role in the management of patients with differentiated thyroid carcinoma (DTC), to detect normal thyroid remnants and recurrent or metastatic disease. A focus of I-131 accumulation outside the thyroid bed and the areas of physiological uptake is strongly suggestive of a distant functioning metastasis. However, many false-positive I-131 WBS findings have been reported in the literature. We describe a series of 11 personal cases of patients with DTC, collected from 1992 to 2011, in whom diagnostic or post-treatment WBS showed false-positive retention of I-131 in various locations. False-positive accumulations of I-131 on WBS may be classified according to the underlying pathophysiological mechanisms: external and internal contaminations by body secretions, ectopic normal thyroid and gastric tissues, inflammatory and infectious diseases, benign and malignant tumors, cysts and effusions of serous cavities, thymic uptake, and other non classified causes. Clinicians must be aware of possible false-positive findings to avoid misinterpretations of the I-131 WBS, which could lead to inappropriate treatments. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

Comparing diagnostic tests on benefit-risk.

PubMed

Pennello, Gene; Pantoja-Galicia, Norberto; Evans, Scott

2016-01-01

Comparing diagnostic tests on accuracy alone can be inconclusive. For example, a test may have better sensitivity than another test yet worse specificity. Comparing tests on benefit risk may be more conclusive because clinical consequences of diagnostic error are considered. For benefit-risk evaluation, we propose diagnostic yield, the expected distribution of subjects with true positive, false positive, true negative, and false negative test results in a hypothetical population. We construct a table of diagnostic yield that includes the number of false positive subjects experiencing adverse consequences from unnecessary work-up. We then develop a decision theory for evaluating tests. The theory provides additional interpretation to quantities in the diagnostic yield table. It also indicates that the expected utility of a test relative to a perfect test is a weighted accuracy measure, the average of sensitivity and specificity weighted for prevalence and relative importance of false positive and false negative testing errors, also interpretable as the cost-benefit ratio of treating non-diseased and diseased subjects. We propose plots of diagnostic yield, weighted accuracy, and relative net benefit of tests as functions of prevalence or cost-benefit ratio. Concepts are illustrated with hypothetical screening tests for colorectal cancer with test positive subjects being referred to colonoscopy.
False memories, but not false beliefs, affect implicit attitudes for food preferences.

PubMed

Howe, David; Anderson, Rachel J; Dewhurst, Stephen A

2017-09-01

Previous studies have found that false memories and false beliefs of childhood experiences can have attitudinal consequences. Previous studies have, however, focused exclusively on explicit attitude measures without exploring whether implicit attitudes are similarly affected. Using a false feedback/imagination inflation paradigm, false memories and beliefs of enjoying a certain food as a child were elicited in participants, and their effects were assessed using both explicit attitude measures (self-report questionnaires) and implicit measures (a Single-Target Implicit Association Test). Positive changes in explicit attitudes were observed both in participants with false memories and participants with false beliefs. In contrast, only participants with false memories exhibited more positive implicit attitudes. The findings are discussed in terms of theories of explicit and implicit attitudes. Copyright © 2017 Elsevier B.V. All rights reserved.
Assessment of potential false positives via orbitrap-based untargeted lipidomics from rat tissues.

PubMed

Xu, Lina; Wang, Xueying; Jiao, Yupei; Liu, Xiaohui

2018-02-01

Untargeted lipidomics is increasingly popular due to the broad coverage of lipid species. Data dependent MS/MS acquisition is commonly used in order to acquire sufficient information for confident lipid assignment. However, although lipids are identified based on MS/MS confirmation, a number of false positives are still observed. Here, we discuss several causes of introducing lipid false identifications in untargeted analysis. Phosphotidylcholines and cholesteryl esters generate in-source fragmentation to produce dimethylated phosphotidylethanolamine and free cholesterol. Dimerization of fatty acid results in false identification of fatty acid ester of hydroxyl fatty acid. Realizing these false positives is able to improve confidence of results acquired from untargeted analysis. Besides, thresholds are established for lipids identified using LipidSearch v4.1.16 software to reduce unreliable results. Copyright © 2017 Elsevier B.V. All rights reserved.
A Defense of Semantic Minimalism

ERIC Educational Resources Information Center

Kim, Su

2012-01-01

Semantic Minimalism is a position about the semantic content of declarative sentences, i.e., the content that is determined entirely by syntax. It is defined by the following two points: "Point 1": The semantic content is a complete/truth-conditional proposition. "Point 2": The semantic content is useful to a theory of…
47 CFR 15.13 - Incidental radiators.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 47 Telecommunication 1 2010-10-01 2010-10-01 false Incidental radiators. 15.13 Section 15.13 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL RADIO FREQUENCY DEVICES General § 15.13 Incidental radiators. Manufacturers of these devices shall employ good engineering practices to minimize the risk of...
Diagnosing periprosthetic infection: false-positive intraoperative Gram stains.

PubMed

Oethinger, Margret; Warner, Debra K; Schindler, Susan A; Kobayashi, Hideo; Bauer, Thomas W

2011-04-01

Intraoperative Gram stains have a reported low sensitivity but high specificity when used to help diagnose periprosthetic infections. In early 2008, we recognized an unexpectedly high frequency of apparent false-positive Gram stains from revision arthroplasties. The purpose of this report is to describe the cause of these false-positive test results. We calculated the sensitivity and specificity of all intraoperative Gram stains submitted from revision arthroplasty cases during a 3-month interval using microbiologic cultures of the same samples as the gold standard. Methods of specimen harvesting, handling, transport, distribution, specimen processing including tissue grinding/macerating, Gram staining, and interpretation were studied. After a test modification, results of specimens were prospectively collected for a second 3-month interval, and the sensitivity and specificity of intraoperative Gram stains were calculated. The retrospective review of 269 Gram stains submitted from revision arthroplasties indicated historic sensitivity and specificity values of 23% and 92%, respectively. Systematic analysis of all steps of the procedure identified Gram-stained but nonviable bacteria in commercial broth reagents used as diluents for maceration of periprosthetic membranes before Gram staining and culture. Polymerase chain reaction and sequencing showed mixed bacterial DNA. Evaluation of 390 specimens after initiating standardized Millipore filtering of diluent fluid revealed a reduced number of positive Gram stains, yielding 9% sensitivity and 99% specificity. Clusters of false-positive Gram stains have been reported in other clinical conditions. They are apparently rare related to diagnosing periprosthetic infections but have severe consequences if used to guide treatment. Even occasional false-positive Gram stains should prompt review of laboratory methods. Our observations implicate dead bacteria in microbiologic reagents as potential sources of false-positive Gram stains.
Risk of Breast Cancer in Women with False-Positive Results according to Mammographic Features.

PubMed

Castells, Xavier; Torá-Rocamora, Isabel; Posso, Margarita; Román, Marta; Vernet-Tomas, Maria; Rodríguez-Arana, Ana; Domingo, Laia; Vidal, Carmen; Baré, Marisa; Ferrer, Joana; Quintana, María Jesús; Sánchez, Mar; Natal, Carmen; Espinàs, Josep A; Saladié, Francina; Sala, María

2016-08-01

Purpose To assess the risk of breast cancer in women with false-positive screening results according to radiologic classification of mammographic features. Materials and Methods Review board approval was obtained, with waiver of informed consent. This retrospective cohort study included 521 200 women aged 50-69 years who underwent screening as part of the Spanish Breast Cancer Screening Program between 1994 and 2010 and who were observed until December 2012. Cox proportional hazards regression analysis was used to estimate the age-adjusted hazard ratio (HR) of breast cancer and the 95% confidence interval (CI) in women with false-positive mammograms as compared with women with negative mammograms. Separate models were adjusted for screen-detected and interval cancers and for screen-film and digital mammography. Time without a breast cancer diagnosis was plotted by using Kaplan-Meier curves. Results When compared with women with negative mammograms, the age-adjusted HR of cancer in women with false-positive results was 1.84 (95% CI: 1.73, 1.95; P < .001). The risk was higher in women who had calcifications, whether they were (HR, 2.73; 95% CI: 2.28, 3.28; P < .001) or were not (HR, 2.24; 95% CI: 2.02, 2.48; P < .001) associated with masses. Women in whom mammographic features showed changes in subsequent false-positive results were those who had the highest risk (HR, 9.13; 95% CI: 8.28, 10.07; P < .001). Conclusion Women with false-positive results had an increased risk of breast cancer, particularly women who had calcifications at mammography. Women who had more than one examination with false-positive findings and in whom the mammographic features changed over time had a highly increased risk of breast cancer. Previous mammographic features might yield useful information for further risk-prediction models and personalized follow-up screening protocols. (©) RSNA, 2016 Online supplemental material is available for this article.
Use of minimal invasive extracorporeal circulation in cardiac surgery: principles, definitions and potential benefits. A position paper from the Minimal invasive Extra-Corporeal Technologies international Society (MiECTiS)

PubMed Central

Anastasiadis, Kyriakos; Murkin, John; Antonitsis, Polychronis; Bauer, Adrian; Ranucci, Marco; Gygax, Erich; Schaarschmidt, Jan; Fromes, Yves; Philipp, Alois; Eberle, Balthasar; Punjabi, Prakash; Argiriadou, Helena; Kadner, Alexander; Jenni, Hansjoerg; Albrecht, Guenter; van Boven, Wim; Liebold, Andreas; de Somer, Fillip; Hausmann, Harald; Deliopoulos, Apostolos; El-Essawi, Aschraf; Mazzei, Valerio; Biancari, Fausto; Fernandez, Adam; Weerwind, Patrick; Puehler, Thomas; Serrick, Cyril; Waanders, Frans; Gunaydin, Serdar; Ohri, Sunil; Gummert, Jan; Angelini, Gianni; Falk, Volkmar; Carrel, Thierry

2016-01-01

Minimal invasive extracorporeal circulation (MiECC) systems have initiated important efforts within science and technology to further improve the biocompatibility of cardiopulmonary bypass components to minimize the adverse effects and improve end-organ protection. The Minimal invasive Extra-Corporeal Technologies international Society was founded to create an international forum for the exchange of ideas on clinical application and research of minimal invasive extracorporeal circulation technology. The present work is a consensus document developed to standardize the terminology and the definition of minimal invasive extracorporeal circulation technology as well as to provide recommendations for the clinical practice. The goal of this manuscript is to promote the use of MiECC systems into clinical practice as a multidisciplinary strategy involving cardiac surgeons, anaesthesiologists and perfusionists. PMID:26819269
CD19/CD22 Chimeric Antigen Receptor T Cells and Chemotherapy in Treating Children or Young Adults With Recurrent or Refractory CD19 Positive B Acute Lymphoblastic Leukemia

ClinicalTrials.gov

2017-11-20

B Acute Lymphoblastic Leukemia; CD19 Positive; Minimal Residual Disease; Philadelphia Chromosome Positive; Recurrent Adult Acute Lymphoblastic Leukemia; Recurrent Childhood Acute Lymphoblastic Leukemia; Refractory Acute Lymphoblastic Leukemia
Circulating cell-derived microparticles in patients with minimally symptomatic obstructive sleep apnoea.

PubMed

Ayers, L; Ferry, B; Craig, S; Nicoll, D; Stradling, J R; Kohler, M

2009-03-01

Moderate-severe obstructive sleep apnoea (OSA) has been associated with several pro-atherogenic mechanisms and increased cardiovascular risk, but it is not known if minimally symptomatic OSA has similar effects. Circulating cell-derived microparticles have been shown to have pro-inflammatory, pro-coagulant and endothelial function-impairing effects, as well as to predict subclinical atherosclerosis and cardiovascular risk. In 57 patients with minimally symptomatic OSA, and 15 closely matched control subjects without OSA, AnnexinV-positive, platelet-, leukocyte- and endothelial cell-derived microparticles were measured by flow cytometry. In patients with OSA, median (interquartile range) levels of AnnexinV-positive microparticles were significantly elevated compared with control subjects: 2,586 (1,566-3,964) microL(-1) versus 1,206 (474-2,501) microL(-1), respectively. Levels of platelet-derived and leukocyte-derived microparticles were also significantly higher in patients with OSA (2,267 (1,102-3,592) microL(-1) and 20 (14-31) microL(-1), respectively) compared with control subjects (925 (328-2,068) microL(-1) and 15 (5-23) microL(-1), respectively). Endothelial cell-derived microparticle levels were similar in patients with OSA compared with control subjects (13 (8-25) microL(-1) versus 11 (6-17) microL(-1)). In patients with minimally symptomatic obstructive sleep apnoea, levels of AnnexinV-positive, platelet- and leukocyte-derived microparticles are elevated when compared with closely matched control subjects without obstructive sleep apnoea. These findings suggest that these patients may be at increased cardiovascular risk, despite being minimally symptomatic.
Automatic lung nodule graph cuts segmentation with deep learning false positive reduction

NASA Astrophysics Data System (ADS)

Sun, Wenqing; Huang, Xia; Tseng, Tzu-Liang Bill; Qian, Wei

2017-03-01

To automatic detect lung nodules from CT images, we designed a two stage computer aided detection (CAD) system. The first stage is graph cuts segmentation to identify and segment the nodule candidates, and the second stage is convolutional neural network for false positive reduction. The dataset contains 595 CT cases randomly selected from Lung Image Database Consortium and Image Database Resource Initiative (LIDC/IDRI) and the 305 pulmonary nodules achieved diagnosis consensus by all four experienced radiologists were our detection targets. Consider each slice as an individual sample, 2844 nodules were included in our database. The graph cuts segmentation was conducted in a two-dimension manner, 2733 lung nodule ROIs are successfully identified and segmented. With a false positive reduction by a seven-layer convolutional neural network, 2535 nodules remain detected while the false positive dropped to 31.6%. The average F-measure of segmented lung nodule tissue is 0.8501.
Verification of false-positive blood culture results generated by the BACTEC 9000 series by eubacterial 16S rDNA and panfungal 18S rDNA directed polymerase chain reaction (PCR).

PubMed

Daxboeck, Florian; Dornbusch, Hans Jürgen; Krause, Robert; Assadian, Ojan; Wenisch, Christoph

2004-01-01

A small but significant proportion of blood cultures processed by the BACTEC 9000 series systems is signaled positive, while subsequent Gram's stain and culture on solid media yield no pathogens. In this study, 15 "false-positive" vials (7 aerobes, 8 anaerobes) from 15 patients were investigated for the presence of bacteria and fungi by eubacterial 16S rDNA and panfungal 18S rDNA amplification, respectively. All samples turned out negative by both methods. Most patients (7) had neutropenia, which does not support the theory that high leukocyte counts enhance the generation of false-positive results. In conclusion, the results of this study indicate that false-negative results generated by the BACTEC 9000 series are inherent to the automated detection and not due to the growth of fastidious organisms.
False positive malaria rapid diagnostic test in returning traveler with typhoid fever.

PubMed

Meatherall, Bonnie; Preston, Keith; Pillai, Dylan R

2014-07-09

Rapid diagnostic tests play a pivotal role in the early diagnosis of malaria where microscopy or polymerase chain reaction are not immediately available. We report the case of a 39 year old traveler to Canada who presented with fever, headache, and abdominal pain after visiting friends and relatives in India. While in India, the individual was not ill and had no signs or symptoms of malaria. Laboratory testing upon his return to Canada identified a false positive malaria rapid diagnostic (BinaxNOW® malaria) result for P. falciparum with coincident Salmonella Typhi bacteraemia without rheumatoid or autoimmune factors. Rapid diagnostic test false positivity for malaria coincided with the presence or absence of Salmonella Typhi in the blood. Clinicians should be aware that Salmonella Typhi infection may result in a false positive malaria rapid diagnostic test. The mechanism of this cross-reactivity is not clear.
A novel gamma-fitting statistical method for anti-drug antibody assays to establish assay cut points for data with non-normal distribution.

PubMed

Schlain, Brian; Amaravadi, Lakshmi; Donley, Jean; Wickramasekera, Ananda; Bennett, Donald; Subramanyam, Meena

2010-01-31

In recent years there has been growing recognition of the impact of anti-drug or anti-therapeutic antibodies (ADAs, ATAs) on the pharmacokinetic and pharmacodynamic behavior of the drug, which ultimately affects drug exposure and activity. These anti-drug antibodies can also impact safety of the therapeutic by inducing a range of reactions from hypersensitivity to neutralization of the activity of an endogenous protein. Assessments of immunogenicity, therefore, are critically dependent on the bioanalytical method used to test samples, in which a positive versus negative reactivity is determined by a statistically derived cut point based on the distribution of drug naïve samples. For non-normally distributed data, a novel gamma-fitting method for obtaining assay cut points is presented. Non-normal immunogenicity data distributions, which tend to be unimodal and positively skewed, can often be modeled by 3-parameter gamma fits. Under a gamma regime, gamma based cut points were found to be more accurate (closer to their targeted false positive rates) compared to normal or log-normal methods and more precise (smaller standard errors of cut point estimators) compared with the nonparametric percentile method. Under a gamma regime, normal theory based methods for estimating cut points targeting a 5% false positive rate were found in computer simulation experiments to have, on average, false positive rates ranging from 6.2 to 8.3% (or positive biases between +1.2 and +3.3%) with bias decreasing with the magnitude of the gamma shape parameter. The log-normal fits tended, on average, to underestimate false positive rates with negative biases as large a -2.3% with absolute bias decreasing with the shape parameter. These results were consistent with the well known fact that gamma distributions become less skewed and closer to a normal distribution as their shape parameters increase. Inflated false positive rates, especially in a screening assay, shifts the emphasis to confirm test results in a subsequent test (confirmatory assay). On the other hand, deflated false positive rates in the case of screening immunogenicity assays will not meet the minimum 5% false positive target as proposed in the immunogenicity assay guidance white papers. Copyright 2009 Elsevier B.V. All rights reserved.
Negative affect promotes encoding of and memory for details at the expense of the gist: affect, encoding, and false memories.

PubMed

Storbeck, Justin

2013-01-01

I investigated whether negative affective states enhance encoding of and memory for item-specific information reducing false memories. Positive, negative, and neutral moods were induced, and participants then completed a Deese-Roediger-McDermott (DRM) false-memory task. List items were presented in unique spatial locations or unique fonts to serve as measures for item-specific encoding. The negative mood conditions had more accurate memories for item-specific information, and they also had fewer false memories. The final experiment used a manipulation that drew attention to distinctive information, which aided learning for DRM words, but also promoted item-specific encoding. For the condition that promoted item-specific encoding, false memories were reduced for positive and neutral mood conditions to a rate similar to that of the negative mood condition. These experiments demonstrated that negative affective cues promote item-specific processing reducing false memories. People in positive and negative moods encode events differently creating different memories for the same event.
True detection limits in an experimental linearly heteroscedastic system. Part 1

NASA Astrophysics Data System (ADS)

Voigtman, Edward; Abraham, Kevin T.

2011-11-01

Using a lab-constructed laser-excited filter fluorimeter deliberately designed to exhibit linearly heteroscedastic, additive Gaussian noise, it has been shown that accurate estimates may be made of the true theoretical Currie decision levels ( YC and XC) and true Currie detection limits ( YD and XD) for the detection of rhodamine 6 G tetrafluoroborate in ethanol. The obtained experimental values, for 5% probability of false positives and 5% probability of false negatives, were YC = 56.1 mV, YD = 125. mV, XC = 0.132 μg /mL and XD = 0.294 μg /mL. For 5% probability of false positives and 1% probability of false negatives, the obtained detection limits were YD = 158. mV and XD = 0.372 μg /mL. These decision levels and corresponding detection limits were shown to pass the ultimate test: they resulted in observed probabilities of false positives and false negatives that were statistically equivalent to the a priori specified values.
Genome-wide assessment of differential translations with ribosome profiling data

PubMed Central

Xiao, Zhengtao; Zou, Qin; Liu, Yu; Yang, Xuerui

2016-01-01

The closely regulated process of mRNA translation is crucial for precise control of protein abundance and quality. Ribosome profiling, a combination of ribosome foot-printing and RNA deep sequencing, has been used in a large variety of studies to quantify genome-wide mRNA translation. Here, we developed Xtail, an analysis pipeline tailored for ribosome profiling data that comprehensively and accurately identifies differentially translated genes in pairwise comparisons. Applied on simulated and real datasets, Xtail exhibits high sensitivity with minimal false-positive rates, outperforming existing methods in the accuracy of quantifying differential translations. With published ribosome profiling datasets, Xtail does not only reveal differentially translated genes that make biological sense, but also uncovers new events of differential translation in human cancer cells on mTOR signalling perturbation and in human primary macrophages on interferon gamma (IFN-γ) treatment. This demonstrates the value of Xtail in providing novel insights into the molecular mechanisms that involve translational dysregulations. PMID:27041671
Multi-Criteria Decision Making Approaches for Quality Control of Genome-Wide Association Studies

PubMed Central

Malovini, Alberto; Rognoni, Carla; Puca, Annibale; Bellazzi, Riccardo

2009-01-01

Experimental errors in the genotyping phases of a Genome-Wide Association Study (GWAS) can lead to false positive findings and to spurious associations. An appropriate quality control phase could minimize the effects of this kind of errors. Several filtering criteria can be used to perform quality control. Currently, no formal methods have been proposed for taking into account at the same time these criteria and the experimenter’s preferences. In this paper we propose two strategies for setting appropriate genotyping rate thresholds for GWAS quality control. These two approaches are based on the Multi-Criteria Decision Making theory. We have applied our method on a real dataset composed by 734 individuals affected by Arterial Hypertension (AH) and 486 nonagenarians without history of AH. The proposed strategies appear to deal with GWAS quality control in a sound way, as they lead to rationalize and make explicit the experimenter’s choices thus providing more reproducible results. PMID:21347174
Trimodal spectra for high discrimination of benign and malignant prostate tissue

NASA Astrophysics Data System (ADS)

Al Salhi, Mohamad; Masilamani, Vadivel; Trinka, Vijmasi; Rabah, Danny; Al Turki, Mohammed R.

2011-02-01

High false positives and over diagnosis is a major problem with management of prostate cancer. A non-invasive or a minimally invasive technique to accurately distinguish malignant prostate cancers from benign tumors will be extremely helpful to overcome this problem. In this paper, we had used three different fluorescence spectroscopy techniques viz., Fluorescence Emission Spectrum (FES), Stokes' Shift Spectrum (SSS) and Reflectance Spectrum (RS) to discriminate benign prostate tumor tissues (N=12) and malignant prostate cancer tissues (N=8). These fluorescence techniques were used to determine the relative concentration of naturally occurring biomolecules such as tryptophan, elastin, NADH and flavin which are found to be out of proportion in cancer tissues. Our studies show that combining all three techniques, benign and malignant prostate tissues could be classified with accuracy greater than 90%. This preliminary report is based on in vitro spectroscopy analysis. However, by employing fluorescence endoscopy techniques, this can be extended to in vivo analysis as well. This technique has the potential to identify malignant prostate tissues without surgery.
Rational Methods for the Selection of Diverse Screening Compounds

PubMed Central

Huggins, David J.; Venkitaraman, Ashok R.; Spring, David R.

2016-01-01

Traditionally a pursuit of large pharmaceutical companies, high-throughput screening assays are becoming increasingly common within academic and government laboratories. This shift has been instrumental in enabling projects that have not been commercially viable, such as chemical probe discovery and screening against high risk targets. Once an assay has been prepared and validated, it must be fed with screening compounds. Crafting a successful collection of small molecules for screening poses a significant challenge. An optimized collection will minimize false positives whilst maximizing hit rates of compounds that are amenable to lead generation and optimization. Without due consideration of the relevant protein targets and the downstream screening assays, compound filtering and selection can fail to explore the great extent of chemical diversity and eschew valuable novelty. Herein, we discuss the different factors to be considered and methods that may be employed when assembling a structurally diverse compound screening collection. Rational methods for selecting diverse chemical libraries are essential for their effective use in high-throughput screens. PMID:21261294

Qualitative reasoning for biological network inference from systematic perturbation experiments.

PubMed

Badaloni, Silvana; Di Camillo, Barbara; Sambo, Francesco

2012-01-01

The systematic perturbation of the components of a biological system has been proven among the most informative experimental setups for the identification of causal relations between the components. In this paper, we present Systematic Perturbation-Qualitative Reasoning (SPQR), a novel Qualitative Reasoning approach to automate the interpretation of the results of systematic perturbation experiments. Our method is based on a qualitative abstraction of the experimental data: for each perturbation experiment, measured values of the observed variables are modeled as lower, equal or higher than the measurements in the wild type condition, when no perturbation is applied. The algorithm exploits a set of IF-THEN rules to infer causal relations between the variables, analyzing the patterns of propagation of the perturbation signals through the biological network, and is specifically designed to minimize the rate of false positives among the inferred relations. Tested on both simulated and real perturbation data, SPQR indeed exhibits a significantly higher precision than the state of the art.
Finding Qualitative Research Evidence for Health Technology Assessment.

PubMed

DeJean, Deirdre; Giacomini, Mita; Simeonov, Dorina; Smith, Andrea

2016-08-01

Health technology assessment (HTA) agencies increasingly use reviews of qualitative research as evidence for evaluating social, experiential, and ethical aspects of health technologies. We systematically searched three bibliographic databases (MEDLINE, CINAHL, and Social Science Citation Index [SSCI]) using published search filters or "hedges" and our hybrid filter to identify qualitative research studies pertaining to chronic obstructive pulmonary disease and early breast cancer. The search filters were compared in terms of sensitivity, specificity, and precision. Our screening by title and abstract revealed that qualitative research constituted only slightly more than 1% of all published research on each health topic. The performance of the published search filters varied greatly across topics and databases. Compared with existing search filters, our hybrid filter demonstrated a consistently high sensitivity across databases and topics, and minimized the resource-intensive process of sifting through false positives. We identify opportunities for qualitative health researchers to improve the uptake of qualitative research into evidence-informed policy making. © The Author(s) 2016.
Twenty-Five Centuries of Quantum Physics: From Pythagoras to Us, and from Subjectivism to Realism

NASA Astrophysics Data System (ADS)

Bunge, Mario

Three main theses are proposed. The first is that the idea of a quantum or minimal unit is not peculiar to quantum theory, since it already occurs in the classical theories of elasticity and electrolysis. Second, the peculiarities of the objects described by quantum theory are the following: their basic laws are probabilistic; some of their properties, such as position and energy, are blunt rather than sharp; two particles that were once together continue to be associated even after becoming spatially separated; and the vacuum has physical properties, so that it is a kind of matter. Third, the orthodox or Copenhagen interpretation of the theory is false, and may conveniently be replaced with a realist (though not classicist) interpretation. Heisenberg's inequality, Schrödinger's cat and Zeno's quantum paradox are discussed in the light of the two rival interpretations. It is also shown that the experiments that falsified Bell's inequality do not refute realism but the classicism inherent in hidden variables theories.
Informational need of emotional stress

NASA Astrophysics Data System (ADS)

Simonov, P. V.; Frolov, M. V.

According to the informational theory of emotions[1], emotions in humans depend on the power of some need (motivation) and the estimation by the subject of the probability (possibility) of the need staisfaction (the goal achievement). Low probability of need satisfaction leads to negative emotions, actively minimized by the subject. Increased probability of satisfaction, as compared to earlier forecast, generates positive emotions, which the subject tries to maximize, i.e. to enhance, to prolong, to repeat. The informational theory of emotions encompasses their reflective function, the laws of their appearance, the regulatory significance of emotions, and their role in organization of behavior. The level of emotional stress influences the operator's performance. A decrease in the emotional tonus leads to drowsiness, lack of vigilance, missing of significant signals and to slower reactions. An extremely high stress level disorganizes the activity, complicates it with a trend toward incorrect actions and reactions to insignificant signals (false alarms). The neurophysiological mechanisms of the influence of emotions on perceptual activity and operator performance as well as the significance of individuality are discussed.
Hybrid Model-Based and Data-Driven Fault Detection and Diagnostics for Commercial Buildings

DOE Office of Scientific and Technical Information (OSTI.GOV)

Frank, Stephen; Heaney, Michael; Jin, Xin

Commercial buildings often experience faults that produce undesirable behavior in building systems. Building faults waste energy, decrease occupants' comfort, and increase operating costs. Automated fault detection and diagnosis (FDD) tools for buildings help building owners discover and identify the root causes of faults in building systems, equipment, and controls. Proper implementation of FDD has the potential to simultaneously improve comfort, reduce energy use, and narrow the gap between actual and optimal building performance. However, conventional rule-based FDD requires expensive instrumentation and valuable engineering labor, which limit deployment opportunities. This paper presents a hybrid, automated FDD approach that combines building energymore » models and statistical learning tools to detect and diagnose faults noninvasively, using minimal sensors, with little customization. We compare and contrast the performance of several hybrid FDD algorithms for a small security building. Our results indicate that the algorithms can detect and diagnose several common faults, but more work is required to reduce false positive rates and improve diagnosis accuracy.« less
Hybrid Model-Based and Data-Driven Fault Detection and Diagnostics for Commercial Buildings: Preprint

DOE Office of Scientific and Technical Information (OSTI.GOV)

Frank, Stephen; Heaney, Michael; Jin, Xin

Commercial buildings often experience faults that produce undesirable behavior in building systems. Building faults waste energy, decrease occupants' comfort, and increase operating costs. Automated fault detection and diagnosis (FDD) tools for buildings help building owners discover and identify the root causes of faults in building systems, equipment, and controls. Proper implementation of FDD has the potential to simultaneously improve comfort, reduce energy use, and narrow the gap between actual and optimal building performance. However, conventional rule-based FDD requires expensive instrumentation and valuable engineering labor, which limit deployment opportunities. This paper presents a hybrid, automated FDD approach that combines building energymore » models and statistical learning tools to detect and diagnose faults noninvasively, using minimal sensors, with little customization. We compare and contrast the performance of several hybrid FDD algorithms for a small security building. Our results indicate that the algorithms can detect and diagnose several common faults, but more work is required to reduce false positive rates and improve diagnosis accuracy.« less
RED NOISE VERSUS PLANETARY INTERPRETATIONS IN THE MICROLENSING EVENT OGLE-2013-BLG-446

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bachelet, E.; Bramich, D. M.; AlSubai, K.

2015-10-20

For all exoplanet candidates, the reliability of a claimed detection needs to be assessed through a careful study of systematic errors in the data to minimize the false positives rate. We present a method to investigate such systematics in microlensing data sets using the microlensing event OGLE-2013-BLG-0446 as a case study. The event was observed from multiple sites around the world and its high magnification (A{sub max} ∼ 3000) allowed us to investigate the effects of terrestrial and annual parallax. Real-time modeling of the event while it was still ongoing suggested the presence of an extremely low-mass companion (∼3M{sub ⨁})more » to the lensing star, leading to substantial follow-up coverage of the light curve. We test and compare different models for the light curve and conclude that the data do not favor the planetary interpretation when systematic errors are taken into account.« less
Systematic Identification of MCU Modulators by Orthogonal Interspecies Chemical Screening.

PubMed

Arduino, Daniela M; Wettmarshausen, Jennifer; Vais, Horia; Navas-Navarro, Paloma; Cheng, Yiming; Leimpek, Anja; Ma, Zhongming; Delrio-Lorenzo, Alba; Giordano, Andrea; Garcia-Perez, Cecilia; Médard, Guillaume; Kuster, Bernhard; García-Sancho, Javier; Mokranjac, Dejana; Foskett, J Kevin; Alonso, M Teresa; Perocchi, Fabiana

2017-08-17

The mitochondrial calcium uniporter complex is essential for calcium (Ca 2+ ) uptake into mitochondria of all mammalian tissues, where it regulates bioenergetics, cell death, and Ca 2+ signal transduction. Despite its involvement in several human diseases, we currently lack pharmacological agents for targeting uniporter activity. Here we introduce a high-throughput assay that selects for human MCU-specific small-molecule modulators in primary drug screens. Using isolated yeast mitochondria, reconstituted with human MCU, its essential regulator EMRE, and aequorin, and exploiting a D-lactate- and mannitol/sucrose-based bioenergetic shunt that greatly minimizes false-positive hits, we identify mitoxantrone out of more than 600 clinically approved drugs as a direct selective inhibitor of human MCU. We validate mitoxantrone in orthogonal mammalian cell-based assays, demonstrating that our screening approach is an effective and robust tool for MCU-specific drug discovery and, more generally, for the identification of compounds that target mitochondrial functions. Copyright © 2017 Elsevier Inc. All rights reserved.
Developing Methodologies to Find Abbreviated Laboratory Test Names in Narrative Clinical Documents by Generating High Quality Q-Grams.

PubMed

Kim, Kyungmo; Choi, Jinwook

2017-01-01

Laboratory test names are used as basic information to diagnose diseases. However, this kind of medical information is usually written in a natural language. To find this information, lexicon based methods have been good solutions but they cannot find terms that do not have abbreviated expressions, such as "neuts" that means "neutrophils". To address this issue, similar word matching can be used; however, it can be disadvantageous because of significant false positives. Moreover, processing time is longer as the size of terms is bigger. Therefore, we suggest a novel q-gram based algorithm, named modified triangular area filtering, to find abbreviated laboratory test terms in clinical documents, minimizing the possibility to impair the lexicons' precision. In addition, we found the terms using the methodology with reasonable processing time. The results show that this method can achieve 92.54 precision, 87.72 recall, 90.06 f1-score in test sets when edit distance threshold(τ) = 3.
Detection of genomic loci associated with environmental variables using generalized linear mixed models.

PubMed

Lobréaux, Stéphane; Melodelima, Christelle

2015-02-01

We tested the use of Generalized Linear Mixed Models to detect associations between genetic loci and environmental variables, taking into account the population structure of sampled individuals. We used a simulation approach to generate datasets under demographically and selectively explicit models. These datasets were used to analyze and optimize GLMM capacity to detect the association between markers and selective coefficients as environmental data in terms of false and true positive rates. Different sampling strategies were tested, maximizing the number of populations sampled, sites sampled per population, or individuals sampled per site, and the effect of different selective intensities on the efficiency of the method was determined. Finally, we apply these models to an Arabidopsis thaliana SNP dataset from different accessions, looking for loci associated with spring minimal temperature. We identified 25 regions that exhibit unusual correlations with the climatic variable and contain genes with functions related to temperature stress. Copyright © 2014 Elsevier Inc. All rights reserved.
Detecting and Discriminating Gravitational Microlensing in the SuperMACHO Survey

NASA Astrophysics Data System (ADS)

Garg, Arti

2010-02-01

The SuperMACHO Project is a 5 year survey to determine the nature of the lens population responsible for the excess gravitational microlensing rate toward the Large Magellanic Cloud observed by the MACHO project. The MACHO results indicate a large population of compact lenses toward the clouds, and the observed lensing rate is consistent with a Milky Way halo comprised of up to ˜20% Massive Compact Halo Objects (MACHO's), dark matter that is most likely baryonic. This work describes the method by which gravitational microlensing is detected in the SuperMACHO survey. Based on the MACHO findings and the SuperMACHO observing strategy and selection criteria, we expect <10-6 of the sources monitored to be lensed at any time. Our detection criteria are designed to minimize false positives while preserving a statistically significant detection rate. We provide an overview of the detection criteria. We also discuss the selection criteria used to discriminate between microlensing and other astrophysical transients. )
Variant-aware saturating mutagenesis using multiple Cas9 nucleases identifies regulatory elements at trait-associated loci.

PubMed

Canver, Matthew C; Lessard, Samuel; Pinello, Luca; Wu, Yuxuan; Ilboudo, Yann; Stern, Emily N; Needleman, Austen J; Galactéros, Frédéric; Brugnara, Carlo; Kutlar, Abdullah; McKenzie, Colin; Reid, Marvin; Chen, Diane D; Das, Partha Pratim; A Cole, Mitchel; Zeng, Jing; Kurita, Ryo; Nakamura, Yukio; Yuan, Guo-Cheng; Lettre, Guillaume; Bauer, Daniel E; Orkin, Stuart H

2017-04-01

Cas9-mediated, high-throughput, saturating in situ mutagenesis permits fine-mapping of function across genomic segments. Disease- and trait-associated variants identified in genome-wide association studies largely cluster at regulatory loci. Here we demonstrate the use of multiple designer nucleases and variant-aware library design to interrogate trait-associated regulatory DNA at high resolution. We developed a computational tool for the creation of saturating-mutagenesis libraries with single or multiple nucleases with incorporation of variants. We applied this methodology to the HBS1L-MYB intergenic region, which is associated with red-blood-cell traits, including fetal hemoglobin levels. This approach identified putative regulatory elements that control MYB expression. Analysis of genomic copy number highlighted potential false-positive regions, thus emphasizing the importance of off-target analysis in the design of saturating-mutagenesis experiments. Together, these data establish a widely applicable high-throughput and high-resolution methodology to identify minimal functional sequences within large disease- and trait-associated regions.
A False Positive Dengue Fever Rapid Diagnostic Test Result in a Case of Acute Parvovirus B19 Infection.

PubMed

Izumida, Toshihide; Sakata, Hidenao; Nakamura, Masahiko; Hayashibara, Yumiko; Inasaki, Noriko; Inahata, Ryo; Hasegawa, Sumiyo; Takizawa, Takenori; Kaya, Hiroyasu

2016-01-01

An outbreak of dengue fever occurred in Japan in August 2014. We herein report the case of a 63-year-old man who presented with a persistent fever in September 2014. Acute parvovirus B19 infection led to a false positive finding of dengue fever on a rapid diagnostic test (Panbio Dengue Duo Cassette(TM)). To the best of our knowledge, there are no previous reports of a false positive result for dengue IgM with the dengue rapid diagnostic test. We believe that epidemiological information on the prevalence of parvovirus B19 is useful for guiding the interpretation of a positive result with the dengue rapid diagnostic test.
Two-step glutamate dehydrogenase antigen real-time polymerase chain reaction assay for detection of toxigenic Clostridium difficile.

PubMed

Goldenberg, S D; Cliff, P R; Smith, S; Milner, M; French, G L

2010-01-01

Current diagnosis of Clostridium difficile infection (CDI) relies upon detection of toxins A/B in stool by enzyme immunoassay [EIA(A/B)]. This strategy is unsatisfactory because it has a low sensitivity resulting in significant false negatives. We investigated the performance of a two-step algorithm for diagnosis of CDI using detection of glutamate dehydrogenase (GDH). GDH-positive samples were tested for C. difficile toxin B gene (tcdB) by polymerase chain reaction (PCR). The performance of the two-step protocol was compared with toxin detection by the Meridian Premier EIA kit in 500 consecutive stool samples from patients with suspected CDI. The reference standard among samples that were positive by either EIA(A/B) or GDH testing was culture cytotoxin neutralisation (culture/CTN). Thirty-six (7%) of 500 samples were identified as true positives by culture/CTN. EIA(A/B) identified 14 of the positive specimens with 22 false negatives and two false positives. The two-step protocol identified 34 of the positive samples with two false positives and two false negatives. EIA(A/B) had a sensitivity of 39%, specificity of 99%, positive predictive value of 88% and negative predictive value of 95%. The two-step algorithm performed better, with corresponding values of 94%, 99%, 94% and 99% respectively. Screening for GDH before confirmation of positives by PCR is cheaper than screening all specimens by PCR and is an effective method for routine use. Current EIA(A/B) tests for CDI are of inadequate sensitivity and should be replaced; however, this may result in apparent changes in CDI rates that would need to be explained in national surveillance statistics. Copyright 2009 The Hospital Infection Society. Published by Elsevier Ltd. All rights reserved.
Generalized minimal principle for rotor filaments.

PubMed

Dierckx, Hans; Wellner, Marcel; Bernus, Olivier; Verschelde, Henri

2015-05-01

To a reaction-diffusion medium with an inhomogeneous anisotropic diffusion tensor D, we add a fourth spatial dimension such that the determinant of the diffusion tensor is constant in four dimensions. We propose a generalized minimal principle for rotor filaments, stating that the scroll wave filament strives to minimize its surface area in the higher-dimensional space. As a consequence, stationary scroll wave filaments in the original 3D medium are geodesic curves with respect to the metric tensor G=det(D)D(-1). The theory is confirmed by numerical simulations for positive and negative filament tension and a model with a non-stationary spiral core. We conclude that filaments in cardiac tissue with positive tension preferentially reside or anchor in regions where cardiac cells are less interconnected, such as portions of the cardiac wall with a large number of cleavage planes.
Effects on lung stress of position and different doses of perfluorocarbon in a model of ARDS.

PubMed

López-Aguilar, Josefina; Lucangelo, Umberto; Albaiceta, Guillermo M; Nahum, Avi; Murias, Gastón; Cañizares, Rosario; Oliva, Joan Carles; Romero, Pablo V; Blanch, Lluís

2015-05-01

We determined whether the combination of low dose partial liquid ventilation (PLV) with perfluorocarbons (PFC) and prone positioning improved lung function while inducing minimal stress. Eighteen pigs with acute lung injury were assigned to conventional mechanical ventilation (CMV) or PLV (5 or 10 ml/kg of PFC). Positive end-expiratory pressure (PEEP) trials in supine and prone positions were performed. Data were analyzed by a multivariate polynomial regression model. The interplay between PLV and position depended on the PEEP level. In supine PLV dampened the stress induced by increased PEEP during the trial. The PFC dose of 5 ml/kg was more effective than the dose 10 ml/kg. This effect was not observed in prone. Oxygenation was significantly higher in prone than in supine position mainly at lower levels of PEEP. In conclusion, MV settings should take both gas exchange and stress/strain into account. When protective CMV fails, rescue strategies combining prone positioning and PLV with optimal PEEP should improve gas exchange with minimal stress. Copyright © 2015 Elsevier B.V. All rights reserved.
Robust feature tracking for endoscopic pose estimation and structure recovery

NASA Astrophysics Data System (ADS)

Speidel, S.; Krappe, S.; Röhl, S.; Bodenstedt, S.; Müller-Stich, B.; Dillmann, R.

2013-03-01

Minimally invasive surgery is a highly complex medical discipline with several difficulties for the surgeon. To alleviate these difficulties, augmented reality can be used for intraoperative assistance. For visualization, the endoscope pose must be known which can be acquired with a SLAM (Simultaneous Localization and Mapping) approach using the endoscopic images. In this paper we focus on feature tracking for SLAM in minimally invasive surgery. Robust feature tracking and minimization of false correspondences is crucial for localizing the endoscope. As sensory input we use a stereo endoscope and evaluate different feature types in a developed SLAM framework. The accuracy of the endoscope pose estimation is validated with synthetic and ex vivo data. Furthermore we test the approach with in vivo image sequences from da Vinci interventions.
Wavelet method for CT colonography computer-aided polyp detection.

PubMed

Li, Jiang; Van Uitert, Robert; Yao, Jianhua; Petrick, Nicholas; Franaszek, Marek; Huang, Adam; Summers, Ronald M

2008-08-01

Computed tomographic colonography (CTC) computer aided detection (CAD) is a new method to detect colon polyps. Colonic polyps are abnormal growths that may become cancerous. Detection and removal of colonic polyps, particularly larger ones, has been shown to reduce the incidence of colorectal cancer. While high sensitivities and low false positive rates are consistently achieved for the detection of polyps sized 1 cm or larger, lower sensitivities and higher false positive rates occur when the goal of CAD is to identify "medium"-sized polyps, 6-9 mm in diameter. Such medium-sized polyps may be important for clinical patient management. We have developed a wavelet-based postprocessor to reduce false positives for this polyp size range. We applied the wavelet-based postprocessor to CTC CAD findings from 44 patients in whom 45 polyps with sizes of 6-9 mm were found at segmentally unblinded optical colonoscopy and visible on retrospective review of the CT colonography images. Prior to the application of the wavelet-based postprocessor, the CTC CAD system detected 33 of the polyps (sensitivity 73.33%) with 12.4 false positives per patient, a sensitivity comparable to that of expert radiologists. Fourfold cross validation with 5000 bootstraps showed that the wavelet-based postprocessor could reduce the false positives by 56.61% (p <0.001), to 5.38 per patient (95% confidence interval [4.41, 6.34]), without significant sensitivity degradation (32/45, 71.11%, 95% confidence interval [66.39%, 75.74%], p=0.1713). We conclude that this wavelet-based postprocessor can substantially reduce the false positive rate of our CTC CAD for this important polyp size range.
Tandem mirror plasma confinement apparatus

DOEpatents

Fowler, T. Kenneth

1978-11-14

Apparatus and method for confining a plasma in a center mirror cell by use of two end mirror cells as positively charged end stoppers to minimize leakage of positive particles from the ends of the center mirror cell.
Diagnostic classification of macular ganglion cell and retinal nerve fiber layer analysis: differentiation of false-positives from glaucoma.

PubMed

Kim, Ko Eun; Jeoung, Jin Wook; Park, Ki Ho; Kim, Dong Myung; Kim, Seok Hwan

2015-03-01

To investigate the rate and associated factors of false-positive diagnostic classification of ganglion cell analysis (GCA) and retinal nerve fiber layer (RNFL) maps, and characteristic false-positive patterns on optical coherence tomography (OCT) deviation maps. Prospective, cross-sectional study. A total of 104 healthy eyes of 104 normal participants. All participants underwent peripapillary and macular spectral-domain (Cirrus-HD, Carl Zeiss Meditec Inc, Dublin, CA) OCT scans. False-positive diagnostic classification was defined as yellow or red color-coded areas for GCA and RNFL maps. Univariate and multivariate logistic regression analyses were used to determine associated factors. Eyes with abnormal OCT deviation maps were categorized on the basis of the shape and location of abnormal color-coded area. Differences in clinical characteristics among the subgroups were compared. (1) The rate and associated factors of false-positive OCT maps; (2) patterns of false-positive, color-coded areas on the GCA deviation map and associated clinical characteristics. Of the 104 healthy eyes, 42 (40.4%) and 32 (30.8%) showed abnormal diagnostic classifications on any of the GCA and RNFL maps, respectively. Multivariate analysis revealed that false-positive GCA diagnostic classification was associated with longer axial length and larger fovea-disc angle, whereas longer axial length and smaller disc area were associated with abnormal RNFL maps. Eyes with abnormal GCA deviation map were categorized as group A (donut-shaped round area around the inner annulus), group B (island-like isolated area), and group C (diffuse, circular area with an irregular inner margin in either). The axial length showed a significant increasing trend from group A to C (P=0.001), and likewise, the refractive error was more myopic in group C than in groups A (P=0.015) and B (P=0.014). Group C had thinner average ganglion cell-inner plexiform layer thickness compared with other groups (group A=B>C, P=0.004). Abnormal OCT diagnostic classification should be interpreted with caution, especially in eyes with long axial lengths, large fovea-disc angles, and small optic discs. Our findings suggest that the characteristic patterns of OCT deviation map can provide useful clues to distinguish glaucomatous changes from false-positive findings. Copyright © 2015 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

Mobile chemical detector (AP2C+SP4E) as an aid for medical decision making in the battlefield.

PubMed

Eisenkraft, Arik; Markel, Gal; Simovich, Shirley; Layish, Ido; Hoffman, Azik; Finkelstein, Arseny; Rotman, Eran; Dushnitsky, Tsvika; Krivoy, Amir

2007-09-01

The combination of the AP2C unit with the SP4E kit composes a lightweight mobile detector of chemical warfare agents (CWA), such as nerve and mustard agents, with both vapor- and liquid-sampling capabilities. This apparatus was recently introduced into our military medical units as an aid for detection of CWA on casualties. Importantly, critical information regarding the applicability in the battlefield was absent. In view of the serious consequences that might follow a proclamation of CWA recognition in battlefield, a high false-positive rate positions the utilization of this apparatus as a medical decision tool in question. We have therefore conducted a field experiment to test the false-positive rate as well as analyze possible factors leading to false-positive readings with this device. The experiment was carried out before and after a 4-day army field exercise, using a standard AP2C device, a SP4E surface sampling kit, and a specially designed medical sampling kit for casualties, intended for medical teams. Soldiers were examined at rest, after mild exercise, and after 4 days in the field. The readings with AP2C alone were compared to the combination of AP2C and SP4E and to the medical sampling kit. Various body fluids served as negative controls. Remarkably, we found a false-positive rate of 57% at rest and after mild exercise, and an even higher rate of 64% after the 4-day field exercise with the AP2C detector alone, as compared to almost no false-positive readings with the combination of AP2C and SP4E. Strikingly, the medical sampling kit has yielded numerous false-positive readings, even in normal body fluids such as blood, urine, and saliva. We therefore see no place for using the medical sampling kit due to an unaccepted high rate of false-positive readings. Finally, we have designed an algorithm that uses the entire apparatus of AP2C and SP4E as a reliable validation tool for medical triage in the setting of exposure to nerve agents in the battlefield.
Salzburg Consensus Criteria for Non-Convulsive Status Epilepticus--approach to clinical application.

PubMed

Leitinger, M; Beniczky, S; Rohracher, A; Gardella, E; Kalss, G; Qerama, E; Höfler, J; Hess Lindberg-Larsen, A; Kuchukhidze, G; Dobesberger, J; Langthaler, P B; Trinka, E

2015-08-01

Salzburg Consensus Criteria for diagnosis of Non-Convulsive Status Epilepticus (SCNC) were proposed at the 4th London-Innsbruck Colloquium on status epilepticus in Salzburg (2013). We retrospectively analyzed the EEGs of 50 consecutive nonhypoxic patients with diagnoses of nonconvulsive status epilepticus (NCSE) at discharge and 50 consecutive controls with abnormal EEGs in a large university hospital in Austria. We implemented the American Clinical Neurophysiology Society's Standardized Critical Care EEG Terminology, 2012 version (ACNS criteria) to increase the test performance of SCNC. In patients without preexisting epileptic encephalopathy, the following criteria were applied: (1) more than 25 epileptiform discharges (ED) per 10-second epoch, i.e., >2.5/s and (2) patients with EDs ≤ 2.5/s or rhythmic delta/theta activity (RDT) exceeding 0.5/s AND at least one of the additional criteria: (2a) clinical and EEG improvements from antiepileptic drugs (AEDs), (2b) subtle clinical phenomena, or (2c) typical spatiotemporal evolution. In case of fluctuation without evolution or EEG improvement without clinical improvement, "possible NCSE" was diagnosed. For identification of RDT, the following criteria were compared: (test condition A) continuous delta-theta activity without further rules, (B) ACNS criterion for rhythmic delta activity (RDA), and (C) ACNS criteria for RDA and fluctuation. False positive rate in controls dropped from 28% (condition A) to 2% (B) (p = 0.00039) and finally to 0% (C) (p = 0.000042). Application of test condition C in the group with NCSE gives one false negative (2%). Various EEG patterns were found in patients with NCSE: (1) 8.2%, (2a) 2%, (2b) 12.2%, and (2c) 32.7%. Possible NCSE was diagnosed based on fluctuations in 57.1% and EEG improvement without clinical improvement in 14.2%. The modified SCNC with refined definitions including the ACNS terminology leads to clinically relevant and statistically significant reduction of false positive diagnoses of NCSE and to minimal loss in sensitivity. This article is part of a Special Issue entitled "Status Epilepticus". Copyright © 2015 Elsevier Inc. All rights reserved.
Development of an imaging method for quantifying a large digital PCR droplet

NASA Astrophysics Data System (ADS)

Huang, Jen-Yu; Lee, Shu-Sheng; Hsu, Yu-Hsiang

2017-02-01

Portable devices have been recognized as the future linkage between end-users and lab-on-a-chip devices. It has a user friendly interface and provides apps to interface headphones, cameras, and communication duct, etc. In particular, the digital resolution of cameras installed in smartphones or pads already has a high imaging resolution with a high number of pixels. This unique feature has triggered researches to integrate optical fixtures with smartphone to provide microscopic imaging capabilities. In this paper, we report our study on developing a portable diagnostic tool based on the imaging system of a smartphone and a digital PCR biochip. A computational algorithm is developed to processing optical images taken from a digital PCR biochip with a smartphone in a black box. Each reaction droplet is recorded in pixels and is analyzed in a sRGB (red, green, and blue) color space. Multistep filtering algorithm and auto-threshold algorithm are adopted to minimize background noise contributed from ccd cameras and rule out false positive droplets, respectively. Finally, a size-filtering method is applied to identify the number of positive droplets to quantify target's concentration. Statistical analysis is then performed for diagnostic purpose. This process can be integrated in an app and can provide a user friendly interface without professional training.
Cut-off proposal for the detection of ketamine in hair.

PubMed

Salomone, A; Gerace, E; Diana, P; Romeo, M; Malvaso, V; Di Corcia, D; Vincenti, M

2015-03-01

Ketamine is a powerful anesthetic drug used in both human and veterinary surgery, but it is also commonly misused because of its psychotropic properties. Since the abuse of this drug has been reported in many countries worldwide, its determination in hair samples is offered as a specialist test by hundreds of laboratories. However, unlike other common drugs of abuse, a cut-off level for ketamine in hair has not been fixed yet. Therefore, aim of this study is to propose a concentration value for ketamine in hair analysis, in order to discriminate between chronic and occasional use, and between active use and external contamination. After considering the chemical properties of this molecule, and the experimental data collected in our laboratory or reported in several other published studies, we propose a cut-off level of 0.5ng/mg, as indicative of repeated exposure to ketamine. Additionally, we suggest that the detection of the metabolite norketamine should be mandatory to prove active intake and exclude false positive result from external contamination. Thus, a reasonable cut-off value for norketamine could be fixed at 0.1ng/mg, while the minimal concentration ratio norketamine/ketamine may be positively established at 0.05. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.
24 CFR 941.207 - Displacement, relocation, and acquisition.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 24 Housing and Urban Development 4 2013-04-01 2013-04-01 false Displacement, relocation, and... Displacement, relocation, and acquisition. (a) Minimizing displacement. Consistent with the other goals and... displacement of persons (households, businesses, nonprofit organizations, and farms) as a result of a project...
24 CFR 882.810 - Displacement, relocation, and acquisition.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 24 Housing and Urban Development 4 2011-04-01 2011-04-01 false Displacement, relocation, and... Rehabilitation Single Room Occupancy Program for Homeless Individuals § 882.810 Displacement, relocation, and acquisition. (a) Minimizing displacement. (1) Consistent with the other goals and objectives of this part...
24 CFR 941.207 - Displacement, relocation, and acquisition.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 24 Housing and Urban Development 4 2012-04-01 2012-04-01 false Displacement, relocation, and... Displacement, relocation, and acquisition. (a) Minimizing displacement. Consistent with the other goals and... displacement of persons (households, businesses, nonprofit organizations, and farms) as a result of a project...
24 CFR 882.810 - Displacement, relocation, and acquisition.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 24 Housing and Urban Development 4 2014-04-01 2014-04-01 false Displacement, relocation, and... Rehabilitation Single Room Occupancy Program for Homeless Individuals § 882.810 Displacement, relocation, and acquisition. (a) Minimizing displacement. (1) Consistent with the other goals and objectives of this part...
24 CFR 882.810 - Displacement, relocation, and acquisition.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 24 Housing and Urban Development 4 2012-04-01 2012-04-01 false Displacement, relocation, and... Rehabilitation Single Room Occupancy Program for Homeless Individuals § 882.810 Displacement, relocation, and acquisition. (a) Minimizing displacement. (1) Consistent with the other goals and objectives of this part...
24 CFR 941.207 - Displacement, relocation, and acquisition.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 24 Housing and Urban Development 4 2011-04-01 2011-04-01 false Displacement, relocation, and... Displacement, relocation, and acquisition. (a) Minimizing displacement. Consistent with the other goals and... displacement of persons (households, businesses, nonprofit organizations, and farms) as a result of a project...
24 CFR 882.810 - Displacement, relocation, and acquisition.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 24 Housing and Urban Development 4 2010-04-01 2010-04-01 false Displacement, relocation, and... Rehabilitation Single Room Occupancy Program for Homeless Individuals § 882.810 Displacement, relocation, and acquisition. (a) Minimizing displacement. (1) Consistent with the other goals and objectives of this part...
24 CFR 882.810 - Displacement, relocation, and acquisition.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 24 Housing and Urban Development 4 2013-04-01 2013-04-01 false Displacement, relocation, and... Rehabilitation Single Room Occupancy Program for Homeless Individuals § 882.810 Displacement, relocation, and acquisition. (a) Minimizing displacement. (1) Consistent with the other goals and objectives of this part...
24 CFR 941.207 - Displacement, relocation, and acquisition.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 24 Housing and Urban Development 4 2010-04-01 2010-04-01 false Displacement, relocation, and... Displacement, relocation, and acquisition. (a) Minimizing displacement. Consistent with the other goals and... displacement of persons (households, businesses, nonprofit organizations, and farms) as a result of a project...
30 CFR 817.41 - Hydrologic-balance protection.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 30 Mineral Resources 3 2010-07-01 2010-07-01 false Hydrologic-balance protection. 817.41 Section... ACTIVITIES § 817.41 Hydrologic-balance protection. (a) General. All underground mining and reclamation activities shall be conducted to minimize disturbance of the hydrologic balance within the permit and...
30 CFR 817.41 - Hydrologic-balance protection.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 30 Mineral Resources 3 2011-07-01 2011-07-01 false Hydrologic-balance protection. 817.41 Section... ACTIVITIES § 817.41 Hydrologic-balance protection. (a) General. All underground mining and reclamation activities shall be conducted to minimize disturbance of the hydrologic balance within the permit and...
10 CFR 20.1905 - Exemptions to labeling requirements.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 1 2013-01-01 2013-01-01 false Exemptions to labeling requirements. 20.1905 Section 20.1905 Energy NUCLEAR REGULATORY COMMISSION STANDARDS FOR PROTECTION AGAINST RADIATION Precautionary... have sufficient instruction to minimize radiation exposure while handling or working in the vicinity of...
10 CFR 20.1905 - Exemptions to labeling requirements.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 1 2014-01-01 2014-01-01 false Exemptions to labeling requirements. 20.1905 Section 20.1905 Energy NUCLEAR REGULATORY COMMISSION STANDARDS FOR PROTECTION AGAINST RADIATION Precautionary... have sufficient instruction to minimize radiation exposure while handling or working in the vicinity of...
10 CFR 20.1905 - Exemptions to labeling requirements.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 1 2010-01-01 2010-01-01 false Exemptions to labeling requirements. 20.1905 Section 20.1905 Energy NUCLEAR REGULATORY COMMISSION STANDARDS FOR PROTECTION AGAINST RADIATION Precautionary... have sufficient instruction to minimize radiation exposure while handling or working in the vicinity of...
10 CFR 20.1905 - Exemptions to labeling requirements.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 1 2012-01-01 2012-01-01 false Exemptions to labeling requirements. 20.1905 Section 20.1905 Energy NUCLEAR REGULATORY COMMISSION STANDARDS FOR PROTECTION AGAINST RADIATION Precautionary... have sufficient instruction to minimize radiation exposure while handling or working in the vicinity of...
10 CFR 20.1905 - Exemptions to labeling requirements.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 1 2011-01-01 2011-01-01 false Exemptions to labeling requirements. 20.1905 Section 20.1905 Energy NUCLEAR REGULATORY COMMISSION STANDARDS FOR PROTECTION AGAINST RADIATION Precautionary... have sufficient instruction to minimize radiation exposure while handling or working in the vicinity of...

49 CFR 193.2633 - Interference currents.

Code of Federal Regulations, 2012 CFR

2012-10-01

...: FEDERAL SAFETY STANDARDS Maintenance § 193.2633 Interference currents. (a) Each component that is subject to electrical current interference must be protected by a continuing program to minimize the... 49 Transportation 3 2012-10-01 2012-10-01 false Interference currents. 193.2633 Section 193.2633...
49 CFR 193.2633 - Interference currents.

Code of Federal Regulations, 2014 CFR

2014-10-01

...: FEDERAL SAFETY STANDARDS Maintenance § 193.2633 Interference currents. (a) Each component that is subject to electrical current interference must be protected by a continuing program to minimize the... 49 Transportation 3 2014-10-01 2014-10-01 false Interference currents. 193.2633 Section 193.2633...
49 CFR 193.2633 - Interference currents.

Code of Federal Regulations, 2013 CFR

2013-10-01

...: FEDERAL SAFETY STANDARDS Maintenance § 193.2633 Interference currents. (a) Each component that is subject to electrical current interference must be protected by a continuing program to minimize the... 49 Transportation 3 2013-10-01 2013-10-01 false Interference currents. 193.2633 Section 193.2633...
49 CFR 193.2633 - Interference currents.

Code of Federal Regulations, 2011 CFR

2011-10-01

...: FEDERAL SAFETY STANDARDS Maintenance § 193.2633 Interference currents. (a) Each component that is subject to electrical current interference must be protected by a continuing program to minimize the... 49 Transportation 3 2011-10-01 2011-10-01 false Interference currents. 193.2633 Section 193.2633...
False Positive and False Negative Effects on Network Attacks

NASA Astrophysics Data System (ADS)

Shang, Yilun

2018-01-01

Robustness against attacks serves as evidence for complex network structures and failure mechanisms that lie behind them. Most often, due to detection capability limitation or good disguises, attacks on networks are subject to false positives and false negatives, meaning that functional nodes may be falsely regarded as compromised by the attacker and vice versa. In this work, we initiate a study of false positive/negative effects on network robustness against three fundamental types of attack strategies, namely, random attacks (RA), localized attacks (LA), and targeted attack (TA). By developing a general mathematical framework based upon the percolation model, we investigate analytically and by numerical simulations of attack robustness with false positive/negative rate (FPR/FNR) on three benchmark models including Erdős-Rényi (ER) networks, random regular (RR) networks, and scale-free (SF) networks. We show that ER networks are equivalently robust against RA and LA only when FPR equals zero or the initial network is intact. We find several interesting crossovers in RR and SF networks when FPR is taken into consideration. By defining the cost of attack, we observe diminishing marginal attack efficiency for RA, LA, and TA. Our finding highlights the potential risk of underestimating or ignoring FPR in understanding attack robustness. The results may provide insights into ways of enhancing robustness of network architecture and improve the level of protection of critical infrastructures.
Radar detection with the Neyman-Pearson criterion using supervised-learning-machines trained with the cross-entropy error

NASA Astrophysics Data System (ADS)

Jarabo-Amores, María-Pilar; la Mata-Moya, David de; Gil-Pita, Roberto; Rosa-Zurera, Manuel

2013-12-01

The application of supervised learning machines trained to minimize the Cross-Entropy error to radar detection is explored in this article. The detector is implemented with a learning machine that implements a discriminant function, which output is compared to a threshold selected to fix a desired probability of false alarm. The study is based on the calculation of the function the learning machine approximates to during training, and the application of a sufficient condition for a discriminant function to be used to approximate the optimum Neyman-Pearson (NP) detector. In this article, the function a supervised learning machine approximates to after being trained to minimize the Cross-Entropy error is obtained. This discriminant function can be used to implement the NP detector, which maximizes the probability of detection, maintaining the probability of false alarm below or equal to a predefined value. Some experiments about signal detection using neural networks are also presented to test the validity of the study.
Size and Ultrasound Features Affecting Results of Ultrasound-Guided Fine-Needle Aspiration of Thyroid Nodules.

PubMed

Dong, YiJie; Mao, MinJing; Zhan, WeiWei; Zhou, JianQiao; Zhou, Wei; Yao, JieJie; Hu, YunYun; Wang, Yan; Ye, TingJun

2018-06-01

Our goal was to assess the diagnostic efficacy of ultrasound (US)-guided fine-needle aspiration (FNA) of thyroid nodules according to size and US features. A retrospective correlation was made with 1745 whole thyroidectomy and hemithyroidectomy specimens with preoperative US-guided FNA results. All cases were divided into 5 groups according to nodule size (≤5, 5.1-10, 10.1-15, 15.1-20, and >20 mm). For target nodules, static images and cine clips of conventional US and color Doppler were obtained. Ultrasound images were reviewed and evaluated by two radiologists with at least 5 years US working experience without knowing the results of pathology, and then agreement was achieved. The Bethesda category I rate was higher in nodules larger than 15 mm (P < .05). The diagnostic accuracy was best in nodules of 5 to 10 mm in diameter. The sensitivity, accuracy, PPV, and LR for negative US-guided FNA results were better in nodules with a size range of 5 to 15 mm. The specificity, negative predictive value (NPV), and LR for positive results and the Youden index rose with increasing nodule size. Seventeen false-positive and 60 false-negative results were found in this study. The false-negative rate rose with increasing nodule size. However, the false-positive rate was highest in the group containing the smallest nodules. Nodules with circumscribed margins and those that were nonsolid and nonhypoechoic and had no microcalcifications correlated with Bethesda I FNA results. Nodules with circumscribed margins and those that were nonsolid, heterogeneous, and nonhypoechoic and had increased vascularity correlated with false-negative FNA results. Borders correlated with Bethesda I false-negative and false-positive FNA results. Tiny nodules (≤5 mm) with obscure borders tended to yield false-positive FNA results. Large nodules (>20 mm) with several US features tended to yield false-negative FNA results. © 2017 by the American Institute of Ultrasound in Medicine.
False-belief understanding in frontotemporal dementia and Alzheimer's disease.

PubMed

Fernandez-Duque, Diego; Baird, Jodie A; Black, Sandra E

2009-05-01

The ability to understand other people's behavior in terms of mental states, such as beliefs, desires, and intentions, is central to social interaction. It has been argued that the interpersonal problems of patients with behavioral variant of frontotemporal dementia (FTD-b) are due to a dysfunction of that system. We used first- and second-order false-belief tasks to assess theory-of-mind reasoning in a group of patients with FTD-b and a cognitively matched group of patients with Alzheimer's disease (AD). Both patient groups were equally impaired relative to a healthy elderly group in the cognitively demanding second-order false-belief tasks, revealing that cognitive demands are an important factor in false-belief task performance. Both patient groups reached ceiling performance in the first-order false-belief tasks with minimal cognitive demands, despite the striking difference in their social graces. These results suggest that a conceptual deficit in theory of mind-as measured by the false-belief task-is not at the core of the differences between FTD-b and AD.
Is Empiricism Empirically False? Lessons from Early Nervous Systems.

PubMed

Miłkowski, Marcin

2017-01-01

Recent work on skin-brain thesis (de Wiljes et al. 2015; Keijzer 2015; Keijzer et al. 2013) suggests the possibility of empirical evidence that empiricism is false. It implies that early animals need no traditional sensory receptors to be engaged in cognitive activity. The neural structure required to coordinate extensive sheets of contractile tissue for motility provides the starting point for a new multicellular organized form of sensing. Moving a body by muscle contraction provides the basis for a multicellular organization that is sensitive to external surface structure at the scale of the animal body. In other words, the nervous system first evolved for action, not for receiving sensory input. Thus, sensory input is not required for minimal cognition; only action is. The whole body of an organism, in particular its highly specific animal sensorimotor organization, reflects the bodily and environmental spatiotemporal structure. The skin-brain thesis suggests that, in contrast to empiricist claims that cognition is constituted by sensory systems, cognition may be also constituted by action-oriented feedback mechanisms. Instead of positing the reflex arc as the elementary building block of nervous systems, it proposes that endogenous motor activity is crucial for cognitive processes. In the paper, I discuss the issue whether the skin-brain thesis and its supporting evidence can be really used to overthrow the main tenet of empiricism empirically, by pointing out to cognizing agents that fail to have any sensory apparatus.
Two-level structural sparsity regularization for identifying lattices and defects in noisy images

DOE PAGES

Li, Xin; Belianinov, Alex; Dyck, Ondrej E.; ...

2018-03-09

Here, this paper presents a regularized regression model with a two-level structural sparsity penalty applied to locate individual atoms in a noisy scanning transmission electron microscopy image (STEM). In crystals, the locations of atoms is symmetric, condensed into a few lattice groups. Therefore, by identifying the underlying lattice in a given image, individual atoms can be accurately located. We propose to formulate the identification of the lattice groups as a sparse group selection problem. Furthermore, real atomic scale images contain defects and vacancies, so atomic identification based solely on a lattice group may result in false positives and false negatives.more » To minimize error, model includes an individual sparsity regularization in addition to the group sparsity for a within-group selection, which results in a regression model with a two-level sparsity regularization. We propose a modification of the group orthogonal matching pursuit (gOMP) algorithm with a thresholding step to solve the atom finding problem. The convergence and statistical analyses of the proposed algorithm are presented. The proposed algorithm is also evaluated through numerical experiments with simulated images. The applicability of the algorithm on determination of atom structures and identification of imaging distortions and atomic defects was demonstrated using three real STEM images. In conclusion, we believe this is an important step toward automatic phase identification and assignment with the advent of genomic databases for materials.« less
Two-level structural sparsity regularization for identifying lattices and defects in noisy images

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Xin; Belianinov, Alex; Dyck, Ondrej E.

Here, this paper presents a regularized regression model with a two-level structural sparsity penalty applied to locate individual atoms in a noisy scanning transmission electron microscopy image (STEM). In crystals, the locations of atoms is symmetric, condensed into a few lattice groups. Therefore, by identifying the underlying lattice in a given image, individual atoms can be accurately located. We propose to formulate the identification of the lattice groups as a sparse group selection problem. Furthermore, real atomic scale images contain defects and vacancies, so atomic identification based solely on a lattice group may result in false positives and false negatives.more » To minimize error, model includes an individual sparsity regularization in addition to the group sparsity for a within-group selection, which results in a regression model with a two-level sparsity regularization. We propose a modification of the group orthogonal matching pursuit (gOMP) algorithm with a thresholding step to solve the atom finding problem. The convergence and statistical analyses of the proposed algorithm are presented. The proposed algorithm is also evaluated through numerical experiments with simulated images. The applicability of the algorithm on determination of atom structures and identification of imaging distortions and atomic defects was demonstrated using three real STEM images. In conclusion, we believe this is an important step toward automatic phase identification and assignment with the advent of genomic databases for materials.« less
Highly Specific Binding on Antifouling Zwitterionic Polymer-Coated Microbeads as Measured by Flow Cytometry.

PubMed

van Andel, Esther; de Bus, Ian; Tijhaar, Edwin J; Smulders, Maarten M J; Savelkoul, Huub F J; Zuilhof, Han

2017-11-08

Micron- and nano-sized particles are extensively used in various biomedical applications. However, their performance is often drastically hampered by the nonspecific adsorption of biomolecules, a process called biofouling, which can cause false-positive and false-negative outcomes in diagnostic tests. Although antifouling coatings have been extensively studied on flat surfaces, their use on micro- and nanoparticles remains largely unexplored, despite the widespread experimental (specifically, clinical) uncertainties that arise because of biofouling. Here, we describe the preparation of magnetic micron-sized beads coated with zwitterionic sulfobetaine polymer brushes that display strong antifouling characteristics. These coated beads can then be equipped with recognition elements of choice, to enable the specific binding of target molecules. First, we present a proof of principle with biotin-functionalized beads that are able to specifically bind fluorescently labeled streptavidin from a complex mixture of serum proteins. Moreover, we show the versatility of the method by demonstrating that it is also possible to functionalize the beads with mannose moieties to specifically bind the carbohydrate-binding protein concanavalin A. Flow cytometry was used to show that thus-modified beads only bind specifically targeted proteins, with minimal/near-zero nonspecific protein adsorption from other proteins that are present. These antifouling zwitterionic polymer-coated beads, therefore, provide a significant advancement for the many bead-based diagnostic and other biosensing applications that require stringent antifouling conditions.
Highly Specific Binding on Antifouling Zwitterionic Polymer-Coated Microbeads as Measured by Flow Cytometry

PubMed Central

2017-01-01

Micron- and nano-sized particles are extensively used in various biomedical applications. However, their performance is often drastically hampered by the nonspecific adsorption of biomolecules, a process called biofouling, which can cause false-positive and false-negative outcomes in diagnostic tests. Although antifouling coatings have been extensively studied on flat surfaces, their use on micro- and nanoparticles remains largely unexplored, despite the widespread experimental (specifically, clinical) uncertainties that arise because of biofouling. Here, we describe the preparation of magnetic micron-sized beads coated with zwitterionic sulfobetaine polymer brushes that display strong antifouling characteristics. These coated beads can then be equipped with recognition elements of choice, to enable the specific binding of target molecules. First, we present a proof of principle with biotin-functionalized beads that are able to specifically bind fluorescently labeled streptavidin from a complex mixture of serum proteins. Moreover, we show the versatility of the method by demonstrating that it is also possible to functionalize the beads with mannose moieties to specifically bind the carbohydrate-binding protein concanavalin A. Flow cytometry was used to show that thus-modified beads only bind specifically targeted proteins, with minimal/near-zero nonspecific protein adsorption from other proteins that are present. These antifouling zwitterionic polymer-coated beads, therefore, provide a significant advancement for the many bead-based diagnostic and other biosensing applications that require stringent antifouling conditions. PMID:29064669
The utility of elementary school TOCA-R scores in identifying later criminal court violence among adolescent females.

PubMed

Petras, Hanno; Ialongo, Nicholas; Lambert, Sharon F; Barrueco, Sandra; Schaeffer, Cindy M; Chilcoat, Howard; Kellam, Sheppard

2005-08-01

To evaluate the utility of a teacher-rating instrument (Teacher Observation of Classroom Adaptation-Revised [TOCA-R]) of aggressive behavior during elementary school years in identifying girls at risk of later criminal court violence. A community epidemiological sample of 845 urban public school girls was rated at six time points during elementary school regarding their level of aggressive/disruptive behavior (75% of whom were African American). Criminal violence was measured using juvenile court records. Logistic regression was used to study the strength of the association between early indicators of aggressive behavior and adolescent females' violent outcomes. An extension of the traditional receiver operating characteristics analysis was used to study the accuracy of identifying girls at risk of violence under three different screening and intervention scenarios. For girls, teacher ratings of aggression were a strong and consistent predictor of later violence across grades 1-5 and were strongest in fifth grade. Three screening scenarios were compared to determine the optimal identification threshold. The screening scenario with a focus on minimizing false negatives yielded the highest value (kappa = 0.803). This study supports other studies indicating that early levels of aggressive behavior are strong and robust predictors of later violence among girls but are of limited utility in the early identification of girls at risk, especially when the focus is on reducing both false positives and negatives.
Quantitative analysis of the 26 allergens for cosmetic labeling in fragrance raw materials and perfume oils.

PubMed

Leijs, Hans; Broekhans, Joost; van Pelt, Leon; Mussinan, Cynthia

2005-07-13

The adoption of the 7th amendment of the European Cosmetic Directive 76/768/EEC requires any cosmetic product containing any of 26 raw materials identified by the Scientific Committee on Cosmetic Products and Non-Food Products intended for Consumers as likely to cause a contact allergy when present above certain trigger levels to be declared on the package label. Of these 26, 24 are volatile and can be analyzed by GC. This paper describes a method for the quantitative analysis of these volatile raw materials in perfume ingredients as well as complex perfume compositions. The method uses sequential dual-column GC-MS analysis. The full-scan data acquired minimize the false-positive and false-negative identifications that can be observed with alternate methods based on data acquired in the SIM mode. For each sample, allergen levels are determined on both columns sequentially, leading to two numerical results for each allergen. Quantification limits for each allergen in a perfume mixture based on the analysis of a standard are <4 mg/kg. This is well below the level that would trigger label declaration on the consumer good. Calibration curves for all allergens are linear (r > 0.999) and stable for multiple days. Studies on perfumes spiked with multiple allergens at 30, 50, and 70 mg/kg show recoveries close to nominal values.
Inverse Electrocardiographic Source Localization of Ischemia: An Optimization Framework and Finite Element Solution

PubMed Central

Wang, Dafang; Kirby, Robert M.; MacLeod, Rob S.; Johnson, Chris R.

2013-01-01

With the goal of non-invasively localizing cardiac ischemic disease using body-surface potential recordings, we attempted to reconstruct the transmembrane potential (TMP) throughout the myocardium with the bidomain heart model. The task is an inverse source problem governed by partial differential equations (PDE). Our main contribution is solving the inverse problem within a PDE-constrained optimization framework that enables various physically-based constraints in both equality and inequality forms. We formulated the optimality conditions rigorously in the continuum before deriving finite element discretization, thereby making the optimization independent of discretization choice. Such a formulation was derived for the L2-norm Tikhonov regularization and the total variation minimization. The subsequent numerical optimization was fulfilled by a primal-dual interior-point method tailored to our problem’s specific structure. Our simulations used realistic, fiber-included heart models consisting of up to 18,000 nodes, much finer than any inverse models previously reported. With synthetic ischemia data we localized ischemic regions with roughly a 10% false-negative rate or a 20% false-positive rate under conditions up to 5% input noise. With ischemia data measured from animal experiments, we reconstructed TMPs with roughly 0.9 correlation with the ground truth. While precisely estimating the TMP in general cases remains an open problem, our study shows the feasibility of reconstructing TMP during the ST interval as a means of ischemia localization. PMID:23913980
Evidence-based guideline update: determining brain death in adults: report of the Quality Standards Subcommittee of the American Academy of Neurology.

PubMed

Wijdicks, Eelco F M; Varelas, Panayiotis N; Gronseth, Gary S; Greer, David M

2010-06-08

To provide an update of the 1995 American Academy of Neurology guideline with regard to the following questions: Are there patients who fulfill the clinical criteria of brain death who recover neurologic function? What is an adequate observation period to ensure that cessation of neurologic function is permanent? Are complex motor movements that falsely suggest retained brain function sometimes observed in brain death? What is the comparative safety of techniques for determining apnea? Are there new ancillary tests that accurately identify patients with brain death? A systematic literature search was conducted and included a review of MEDLINE and EMBASE from January 1996 to May 2009. Studies were limited to adults. In adults, there are no published reports of recovery of neurologic function after a diagnosis of brain death using the criteria reviewed in the 1995 American Academy of Neurology practice parameter. Complex-spontaneous motor movements and false-positive triggering of the ventilator may occur in patients who are brain dead. There is insufficient evidence to determine the minimally acceptable observation period to ensure that neurologic functions have ceased irreversibly. Apneic oxygenation diffusion to determine apnea is safe, but there is insufficient evidence to determine the comparative safety of techniques used for apnea testing. There is insufficient evidence to determine if newer ancillary tests accurately confirm the cessation of function of the entire brain.
Neural events that underlie remembering something that never happened.

PubMed

Gonsalves, B; Paller, K A

2000-12-01

We induced people to experience a false-memory illusion by first asking them to visualize common objects when cued with the corresponding word; on some trials, a photograph of the object was presented 1800 ms after the cue word. We then tested their memory for the photographs. Posterior brain potentials in response to words at encoding were more positive if the corresponding object was later falsely remembered as a photograph. Similar brain potentials during the memory test were more positive for true than for false memories. These results implicate visual imagery in the generation of false memories and provide neural correlates of processing differences between true and false memories.
Spatial chaos of Wang tiles with two symbols

NASA Astrophysics Data System (ADS)

Chen, Jin-Yu; Chen, Yu-Jie; Hu, Wen-Guei; Lin, Song-Sun

2016-02-01

This investigation completely classifies the spatial chaos problem in plane edge coloring (Wang tiles) with two symbols. For a set of Wang tiles B , spatial chaos occurs when the spatial entropy h ( B ) is positive. B is called a minimal cycle generator if P ( B ) ≠ 0̸ and P ( B ' ) = 0̸ whenever B ' ⫋ B , where P ( B ) is the set of all periodic patterns on ℤ2 generated by B . Given a set of Wang tiles B , write B = C 1 ∪ C 2 ∪ ⋯ ∪ C k ∪ N , where Cj, 1 ≤ j ≤ k, are minimal cycle generators and B contains no minimal cycle generator except those contained in C1∪C2∪⋯∪Ck. Then, the positivity of spatial entropy h ( B ) is completely determined by C1∪C2∪⋯∪Ck. Furthermore, there are 39 equivalence classes of marginal positive-entropy sets of Wang tiles and 18 equivalence classes of saturated zero-entropy sets of Wang tiles. For a set of Wang tiles B , h ( B ) is positive if and only if B contains a MPE set, and h ( B ) is zero if and only if B is a subset of a SZE set.
Ion-trajectory analysis for micromotion minimization and the measurement of small forces

NASA Astrophysics Data System (ADS)

Gloger, Timm F.; Kaufmann, Peter; Kaufmann, Delia; Baig, M. Tanveer; Collath, Thomas; Johanning, Michael; Wunderlich, Christof

2015-10-01

For experiments with ions confined in a Paul trap, minimization of micromotion is often essential. In order to diagnose and compensate micromotion we have implemented a method that allows for finding the position of the radio-frequency (rf) null reliably and efficiently, in principle, without any variation of direct current (dc) voltages. We apply a trap modulation technique and focus-scanning imaging to extract three-dimensional ion positions for various rf drive powers and analyze the power dependence of the equilibrium position of the trapped ion. In contrast to commonly used methods, the search algorithm directly makes use of a physical effect as opposed to efficient numerical minimization in a high-dimensional parameter space. Using this method we achieve a compensation of the residual electric field that causes excess micromotion in the radial plane of a linear Paul trap down to 0.09 Vm-1 . Additionally, the precise position determination of a single harmonically trapped ion employed here can also be utilized for the detection of small forces. This is demonstrated by determining light pressure forces with a precision of 135 yN. As the method is based on imaging only, it can be applied to several ions simultaneously and is independent of laser direction and thus well suited to be used with, for example, surface-electrode traps.

The inclusion of ADA-SCID in expanded newborn screening by tandem mass spectrometry.

PubMed

la Marca, Giancarlo; Giocaliere, Elisa; Malvagia, Sabrina; Funghini, Silvia; Ombrone, Daniela; Della Bona, Maria Luisa; Canessa, Clementina; Lippi, Francesca; Romano, Francesca; Guerrini, Renzo; Resti, Massimo; Azzari, Chiara

2014-01-01

Severe combined immunodeficiency due to adenosine-deaminase defect (ADA-SCID) is usually deadly in childhood because of severe recurrent infections. When clinical diagnosis is done, permanent damages due to infections or metabolite accumulation are often present. Gene therapy, bone marrow transplantation or enzyme replacement therapy may be effective if started early. The aim of this study was to set-up a robust method suitable for screening with a minimized preparation process and with inexpensive running costs, for diagnosing ADA-SCID by tandem mass spectrometry. ADA-SCID satisfies all the criteria for inclusion in a newborn screening program. We describe a protocol revised to incorporate adenosine and 2-deoxyadenosine testing into an expanded newborn screening program. We assessed the effectiveness of this approach testing dried blood spots from 4 genetically confirmed early-onset and 5 delayed-onset ADA-SCID patients. Reference values were established on 50,000 healthy newborns (deoxyadenosine <0.09μmol/L, adenosine <1.61μmol/L). We also developed a second tier test to distinguish true positives from false positives and improve the positive predictive value of an initial abnormal result. In the first 18 months, the pilot project has identified a newborn with a genetically confirmed defect in adenosine deaminase (ADA) gene. The results show that the method having great simplicity, low cost and low process preparations can be fully applicable to a mass screening program. Copyright © 2013 Elsevier B.V. All rights reserved.
Higher Integrability for Minimizers of the Mumford-Shah Functional

NASA Astrophysics Data System (ADS)

De Philippis, Guido; Figalli, Alessio

2014-08-01

We prove higher integrability for the gradient of local minimizers of the Mumford-Shah energy functional, providing a positive answer to a conjecture of De Giorgi (Free discontinuity problems in calculus of variations. Frontiers in pure and applied mathematics, North-Holland, Amsterdam, pp 55-62, 1991).
Likelihood of early detection of breast cancer in relation to false-positive risk in life-time mammographic screening: population-based cohort study.

PubMed

Otten, J D M; Fracheboud, J; den Heeten, G J; Otto, S J; Holland, R; de Koning, H J; Broeders, M J M; Verbeek, A L M

2013-10-01

Women require balanced, high-quality information when making an informed decision on screening benefits and harms before attending biennial mammographic screening. The cumulative risk of a false-positive recall and/or (small) screen-detected or interval cancer over 13 consecutive screening examinations for women aged 50 from the start of screening were estimated using data from the Nijmegen programme, the Netherlands. Women who underwent 13 successive screens in the period 1975-1976 had a 5.3% cumulative chance of a screen-detected cancer, with a 4.2% risk of at least one false-positive recall. The risk of being diagnosed with interval cancer was 3.7%. Two decades later, these estimates were 6.9%, 7.3% and 2.9%, respectively. The chance of detection of a small, favourable invasive breast cancer, anticipating a normal life-expectancy, rose from 2.3% to 3.7%. Extrapolation to digital screening mammography indicates that the proportion of false-positive results will rise to 16%. Dutch women about to participate in the screening programme can be reassured that the chance of false-positive recall in the Netherlands is relatively low. A new screening policy and improved mammography have increased the detection of an early screening carcinoma and lowering the risk of interval carcinoma.
False-positive results in pharmacoepidemiology and pharmacovigilance.

PubMed

Bezin, Julien; Bosco-Levy, Pauline; Pariente, Antoine

2017-09-01

False-positive constitute an important issue in scientific research. In the domain of drug evaluation, it affects all phases of drug development and assessment, from the very early preclinical studies to the late post-marketing evaluations. The core concern associated with this false-positive is the lack of replicability of the results. Aside from fraud or misconducts, false-positive is often envisioned from the statistical angle, which considers them as a price to pay for type I error in statistical testing, and its inflation in the context of multiple testing. If envisioning this problematic in the context of pharmacoepidemiology and pharmacovigilance however, that both evaluate drugs in an observational settings, information brought by statistical testing and the significance of such should only be considered as additional to the estimates provided and their confidence interval, in a context where differences have to be a clinically meaningful upon everything, and the results appear robust to the biases likely to have affected the studies. In the following article, we consequently illustrate these biases and their consequences in generating false-positive results, through studies and associations between drug use and health outcomes that have been widely disputed. Copyright © 2017 Société française de pharmacologie et de thérapeutique. Published by Elsevier Masson SAS. All rights reserved.
Screening for subclinical Cushing's syndrome in type 2 diabetes mellitus: low false-positive rates with nocturnal salivary cortisol.

PubMed

Gagliardi, L; Chapman, I M; O'Loughlin, P; Torpy, D J

2010-04-01

The diagnosis of subclinical Cushing's syndrome (SCS) is important, but its relative rarity amongst patients with common metabolic disorders requires a simple test with a low false-positive rate. Using nocturnal salivary cortisol (NSC), which we first validated in patients with suspected and proven Cushing's syndrome, we screened 106 overweight patients with type 2 diabetes mellitus, a group at high risk of SCS and nontumoral hypothalamic-pituitary-adrenal axis perturbations. Our hypothesis was that a lower false-positive rate with NSC was likely, compared with that reported with the dexamethasone suppression test (DST) (10-20%), currently the foundation of diagnosis of SCS. No participant had clinically apparent Cushing's syndrome. Three participants had an elevated NSC but further testing excluded SCS. In this study, NSC had a lower false-positive rate (3%) than previously reported for the DST. Given the reported excellent performance of NSC in detection of hypercortisolism, the low false-positive rate in SCS suggests NSC may be superior to the DST for SCS screening. The NSC and DST should be compared directly in metabolic disorder patients; although our data suggest the patient group will need to be substantially larger to definitively determine the optimal screening test. Georg Thieme Verlag KG Stuttgart New York.
Discordant HIV Test Results: Implications on Perinatal and Haemotransfusion Screening for HIV Infection, Cape Coast, Ghana.

PubMed

Tetteh, Ato Kwamena; Agyarko, Edward

2017-01-01

Screening results of 488 pregnant women aged 15-44 years whose blood samples had been tested on-site, using First Response® HIV 1/2, and confirmed with INNO-LIA™ HIV I/II Score were used. Of this total, 178 were reactive (HIV I, 154; HIV II, 2; and HIV I and HIV II, 22). Of the 154 HIV I-reactive samples, 104 were confirmed to be HIV I-positive and 2 were confirmed to be HIV II-positive, while 48 were confirmed to be negative [false positive rate = 17.44% (13.56-21.32)]. The two HIV II samples submitted were confirmed to be negative with the confirmatory test. For the 22 HIV I and HIV II samples, 7 were confirmed to be HIV I-positive and 1 was confirmed to be HIV I- and HIV II-positive, while 14 were confirmed to be negative. Of the 310 nonreactive samples, 6 were confirmed to be HIV I-positive and 1 was confirmed to be HIV II-positive [false negative rate = 5.79% (1.63-8.38)], while 303 were negative. False negative outcomes will remain unconfirmed, with no management options for the client. False negative rate of 5.79% requires attention, as its resultant implications on control of HIV/AIDS could be dire.
Development of CMTD (Curved Multi-Tubed Device) -system III and its application to the needle-insertion for liver.

PubMed

Furusho, Junji; Kobayashi, Hiroshi; Kikuchi, Takehito; Yamamoto, Tatsuro; Tanaka, Hidekazu; Terayama, Motokazu; Monden, Morito

2008-01-01

The purpose of this study is to realize the mechanically-controllable needle-insertion system using the CMTD (Curved Multi-Tube Device) which was developed by Furusho Laboratory. A CMTD, was developed for minimally-invasive surgery and needle insertion. And we use ultrasonograph as a sensing device to detect the position of bible duct or tumor and the orientation and position of the needle which is inserted into liver. This system makes safe minimally-invasive surgery possible, because all complex mechanisms are arranged outside of the body.
Method of preparing a positive electrode for an electrochemical cell

DOEpatents

Tomczuk, Zygmunt

1979-01-01

A method of preparing an electrochemical cell including a metal sulfide as the positive electrode reactant and lithium alloy as the negative electrochemical reactant with an alkali metal, molten salt electrolyte is disclosed which permits the assembly to be accomplished in air. The electrode reactants are introduced in the most part as a sulfide of lithium and the positive electrode metal in a single-phase compound. For instance, Li.sub.2 FeS.sub.2 is a single-phase compound that is produced by the reaction of Li.sub.2 S and FeS. This compound is an intermediate in the positive electrode cycle from FeS.sub.2 to Fe and Li.sub.2 S. Its use minimizes volumetric changes from the assembled to the charged and discharged conditions of the electrode and minimizes electrode material interaction with air and moisture during assembly.
Bias and variance reduction in estimating the proportion of true-null hypotheses

PubMed Central

Cheng, Yebin; Gao, Dexiang; Tong, Tiejun

2015-01-01

When testing a large number of hypotheses, estimating the proportion of true nulls, denoted by \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{upgreek} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} }{}$\\pi _0$\\end{document}, becomes increasingly important. This quantity has many applications in practice. For instance, a reliable estimate of \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{upgreek} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} }{}$\\pi _0$\\end{document} can eliminate the conservative bias of the Benjamini–Hochberg procedure on controlling the false discovery rate. It is known that most methods in the literature for estimating \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{upgreek} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} }{}$\\pi _0$\\end{document} are conservative. Recently, some attempts have been paid to reduce such estimation bias. Nevertheless, they are either over bias corrected or suffering from an unacceptably large estimation variance. In this paper, we propose a new method for estimating \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{upgreek} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} }{}$\\pi _0$\\end{document} that aims to reduce the bias and variance of the estimation simultaneously. To achieve this, we first utilize the probability density functions of false-null \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{upgreek} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} }{}$p$\\end{document}-values and then propose a novel algorithm to estimate the quantity of \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{upgreek} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} }{}$\\pi _0$\\end{document}. The statistical behavior of the proposed estimator is also investigated. Finally, we carry out extensive simulation studies and several real data analysis to evaluate the performance of the proposed estimator. Both simulated and real data demonstrate that the proposed method may improve the existing literature significantly. PMID:24963010
[Evaluation of performance of five bioinformatics software for the prediction of missense mutations].

PubMed

Chen, Qianting; Dai, Congling; Zhang, Qianjun; Du, Juan; Li, Wen

2016-10-01

To study the prediction performance evaluation with five kinds of bioinformatics software (SIFT, PolyPhen2, MutationTaster, Provean, MutationAssessor). From own database for genetic mutations collected over the past five years, Chinese literature database, Human Gene Mutation Database, and dbSNP, 121 missense mutations confirmed by functional studies, and 121 missense mutations suspected to be pathogenic by pedigree analysis were used as positive gold standard, while 242 missense mutations with minor allele frequency (MAF)>5% in dominant hereditary diseases were used as negative gold standard. The selected mutations were predicted with the five software. Based on the results, the performance of the five software was evaluated for their sensitivity, specificity, positive predict value, false positive rate, negative predict value, false negative rate, false discovery rate, accuracy, and receiver operating characteristic curve (ROC). In terms of sensitivity, negative predictive value and false negative rate, the rank was MutationTaster, PolyPhen2, Provean, SIFT, and MutationAssessor. For specificity and false positive rate, the rank was MutationTaster, Provean, MutationAssessor, SIFT, and PolyPhen2. For positive predict value and false discovery rate, the rank was MutationTaster, Provean, MutationAssessor, PolyPhen2, and SIFT. For area under the ROC curve (AUC) and accuracy, the rank was MutationTaster, Provean, PolyPhen2, MutationAssessor, and SIFT. The prediction performance of software may be different when using different parameters. Among the five software, MutationTaster has the best prediction performance.
40 CFR 63.543 - What are my standards for process vents?

Code of Federal Regulations, 2013 CFR

2013-07-01

... available. You must develop and follow standard operating procedures designed to minimize emissions of total... the manufacturer's recommended procedures, if available, and the standard operating procedures... 40 Protection of Environment 10 2013-07-01 2013-07-01 false What are my standards for process...
40 CFR 63.543 - What are my standards for process vents?

Code of Federal Regulations, 2012 CFR

2012-07-01

... available. You must develop and follow standard operating procedures designed to minimize emissions of total... the manufacturer's recommended procedures, if available, and the standard operating procedures... 40 Protection of Environment 10 2012-07-01 2012-07-01 false What are my standards for process...
40 CFR 264.14 - Security.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 26 2011-07-01 2011-07-01 false Security. 264.14 Section 264.14... Standards § 264.14 Security. (a) The owner or operator must prevent the unknowing entry, and minimize the...) for discussion of security requirements at disposal facilities during the post-closure care period...
40 CFR 264.14 - Security.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 27 2012-07-01 2012-07-01 false Security. 264.14 Section 264.14... Standards § 264.14 Security. (a) The owner or operator must prevent the unknowing entry, and minimize the...) for discussion of security requirements at disposal facilities during the post-closure care period...
40 CFR 264.14 - Security.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 27 2013-07-01 2013-07-01 false Security. 264.14 Section 264.14... Standards § 264.14 Security. (a) The owner or operator must prevent the unknowing entry, and minimize the...) for discussion of security requirements at disposal facilities during the post-closure care period...
40 CFR 264.14 - Security.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 26 2014-07-01 2014-07-01 false Security. 264.14 Section 264.14... Standards § 264.14 Security. (a) The owner or operator must prevent the unknowing entry, and minimize the...) for discussion of security requirements at disposal facilities during the post-closure care period...
28 CFR 66.20 - Standards for financial management systems.

Code of Federal Regulations, 2013 CFR

2013-07-01

... subgrant award documents, etc. (7) Cash management. Procedures for minimizing the time elapsing between the... 28 Judicial Administration 2 2013-07-01 2013-07-01 false Standards for financial management... Requirements Financial Administration § 66.20 Standards for financial management systems. (a) A State must...
29 CFR 1470.20 - Standards for financial management systems.

Code of Federal Regulations, 2011 CFR

2011-07-01

... records, contract and subgrant award documents, etc. (7) Cash management. Procedures for minimizing the... 29 Labor 4 2011-07-01 2011-07-01 false Standards for financial management systems. 1470.20 Section... Post-Award Requirements Financial Administration § 1470.20 Standards for financial management systems...
28 CFR 66.20 - Standards for financial management systems.

Code of Federal Regulations, 2014 CFR

2014-07-01

... subgrant award documents, etc. (7) Cash management. Procedures for minimizing the time elapsing between the... 28 Judicial Administration 2 2014-07-01 2014-07-01 false Standards for financial management... Requirements Financial Administration § 66.20 Standards for financial management systems. (a) A State must...
29 CFR 1470.20 - Standards for financial management systems.

Code of Federal Regulations, 2014 CFR

2014-07-01

... records, contract and subgrant award documents, etc. (7) Cash management. Procedures for minimizing the... 29 Labor 4 2014-07-01 2014-07-01 false Standards for financial management systems. 1470.20 Section... Post-Award Requirements Financial Administration § 1470.20 Standards for financial management systems...

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